If you want to take a day completely off in the days prior to the race it is best to do so 2 days prior to the race rather than the day before. If you take the day before the race off you are likely going to be a bit too flat on race day and not ideally prepped.
Four or five days before the race you do your last workout. It should be a dress rehearsal for the race. You wear what you are going to wear in the race, warm up how you plan to warm up and do 3 miles at your marathon goal pace. NO FASTER. This should be very easy, unless you have waited too long to start your taper and you are still very fatigued. If that is the case don't stress you still have time to come right before the race.
The first week of a two week taper should be about 80% of your normal mileage. For our 70 mile a week runner this means about 56 miles. For a one week taper you would just drop to 60% the week of the race. For a 3 week taper you would go 80%, 70%, 60%.
You should do your last long run 7 days prior to the race. It should be no more than 12 miles and no faster than 80% of your goal race pace. 10 days prior to the race you should do a marathon specific workout but it should only be about half of the distance you would normally do. So for example 3x5k at marathon pace instead of the 6x5k or a 7 to 8 mile tempo at marathon pace instead of the 14 to 16 miles you would do at the height of your specific phase. This is not a workout to improve your fitness it is just a chance to keep locked into your marathon rhythm as the race approaches and to keep from over resting and getting sick prior to the race. Early in the week you can also do your last general fitness maintenance workout. It should be about 2/3 the length or intensity of your normal session.
During the specific phase you are not trying to get fitter in the general sense instead you should be almost single-mindedly focused preparing the body for the specific demands of the marathon. The most important of these specific demands is glycogen. I will do a full post on this sometime but the quick and dirty is that if you don't train for the marathon specifically you will run out of glycogen at 20 to 22 miles and you will be unable to hold pace to the finish. The wall. Marathon specific workouts can train your body to use less glycogen per mile leaving more in your tank so that you can finish strong. This is the 'turbo diesel' phenomenon that Renato Canova talks about often. The more widespread use of these training methods among the top athletes in the world is largely responsible for the jump over the last 10 years in marathon performance while 3k to half marathon times have remained comparitively consistent.
Each week you should be doing at least one specific marathon workout. Some examples would be repeats run at marathon pace with recoveries of 1k to 1 mile at 90% of marathon pace, so very close to the same pace as the repeats. The repeats should be 2 to 6 miles long. You can do this workout 3 to 4 times during a specific cycle. Each time the repeats should be longer. So for example in getting ready for the olympic trials I did 3 of these. One was 3 or 4x5k at mp with 1k rest, then 5x5k at mp with 1k rests and then 4x4 miles at mp with 1 mile rests.
Other specific workouts to mix in include Long hard runs at 95% to 97% of marathon pace. These should be 18 to 24 miles in length. These can be among the hardest sessions to recover from and only one or two max should be completed in a specific cycle.
Another great session is alternations where you try to average marathon pace for about 20k alternating efforts about 5% faster than marathon pace, roughly half marathon pace, with recoveries about 5% slower than marathon pace. Your reps and rest should be the same distance and can be as short as 400m/400m and as long as 2k/2k. This session is painfully difficult if not impossible if you don't start building specifically towards it in the base but if you think you may have to run an uneven pace in your goal race, because the course is hilly, or you will be trying to win or need to stick with a certain group, this is a crucial workout. I tried to do it as a one off before my first marathon. I had never done any prep workouts for it. I tried to average 2:15 marathon pace. I lasted only 7k and basically collapsed. Point is two weeks later I ran 2:15:28. I was fit to run the pace even but I would have been in trouble if the race had been a surging one or if I had gone out too fast and needed to settle back and recover mid race.
If you are very fit you can also try one specific block where in single day you do two moderately difficult marathon specific workouts. Together they make for one super hard day. This is a great workout and can lead to breakthroughs but ONLY if you recover fully after it. Even a world class athlete should either jog very lightly or take the day after off and you need to understand it is going to impact your training for at least a week. A few examples would be doing 15k at marathon pace in the morning and than again in the afternoon. Or 10k at 90% mp followed by 10k at marathon pace and repeating that in the afternoon.
Other types of workouts during the specific phase. You must remember that your main focus is the marathon specific workouts but you can and ideally should be doing some moderate workouts to maintain your lactic threshold and vo2max as well as basic speed. You can do whatever you like for these that accomplish that but they should be secondary and never more than 80 or 90% of effort. They cannot be allowed to take away from your specific workouts.
The workouts to build towards specific marathon workouts.
1. Fundmental tempos. You can you read my seperate blog on these but in short they are long tempos 80mins to 3 hours at 80 to 90% of your goal marathon pace. These will build the muscular endurance you need for running a long way at a quick speed. They will also start to teach your body to burn more fat and less glycogen at quicker and quicker speeds.
2. Fartleks and shortish intervals at marathon pace with rests at 80 to 90% of mp. One of my favorites is to start with 6x6mins at marathon pace with 3min rests at about 80% marathon pace. Every week or two I repeat the session but I make the efforts one minute longer. By the time the specific phase starts you are already doing 10 to 12 minute reps at marathon pace so jumping to 3 miles per rep is no big deal. You can of course do something more structured like 20 to 30x1k at marathon pac or 10 to 20x mile at marathon pace. It depends on what you like and what your resources are.
3. Marathon Specific Alternations. These are key if you are going to have to surge or if may get sucked out to fast in your goal marathon. I have mentioned your end goal with these is to end up averaging your marathon pace for 20k or so. To get there you want to start at full distance, 20k, you can do the reps at the length you plan on using throughout your cycle. I view 1k/1k reps as the standard. If you like long hard drives or are very strong in workouts you can go longer. If you struggle with workouts or focusing for longer stretches you can go as short as 500/500 or so. You build this workout by starting with reps that are 5 to 10% faster than mp but with rests that are much slower. So your average pace will be slower than marathon pace. You can start with an average pace of about 80% your marathon pace. Each time you repeat the workout you try to run the rests a little quicker. No single workout will do more to improve your aerobic power and ability to relax and eventually recover at a fast pace.
There you have it the pieces of a full marathon cycle. One could write a book on all the details, heck many have and I would like to get around to one myself someday, but this at least can give you an outline and you can use my other blogs on a lot of these training methods to fill in the blanks. Now go out there and find your full potential. I hope this helps!