Jeremy - Sorry for the delay.
Before just throwing a bunch of workouts out there without any context, he is some background. Renato Canova coaches elite athletes, the best of the best. As such, there are workouts that he has created that are just impossible for regular guys like you and I to even fathom, let alone ever consider attempting. As such, I have tried to maintain the PRINCIPLES that Canova has applied with his workouts to come up with my own progression of workouts for everyday average joes who typically run 60-100mpw like those of us on this thread.
So what are Canova's principles regarding the marathon?
1) You need to have a baseline of lifetime miles in order to tap into your true marathon potential (most average joes are not going to fulfill this requirement, because they haven't spent 10-12 years of their life accumulating the type of miles Canova would recommend for an elite. I understand this. Just realize that you are taking on a watered-down version of Canova and as such, your lifetime miles might be watered down also. I still think that if you have done sufficient preparation in the fundamental and specific stages of a marathon cycle, you will come close to realizing your potential at the specific point in your life. Thus, my recommendations are for average joes - NOT ELITES).
2) To maximize your potential, Canova recommends that the ideal way to train is to extend your ability to hold goal marathon pace at the start of the cycle to your ability to hold it for 26.2 miles at the end of the cycle. Thus workouts at the start of the cycle will begin as two extremes (fast and short, long and slow) and converge upon a common goal: long and at goal pace.
3) The exact progression of workouts is incidental and can be done in a variety of iterations. The point is, every workout should extend your ability to hold a given pace longer than the workout before it. Out of that arises this implied Canova principle - ONCE YOU ARE ABLE TO COMPLETE A CERTAIN WORKOUT/DISTANCE AT A CERTAIN EFFORT, REPEATING THAT WORKOUT/DISTANCE AGAIN AT THE SAME EFFORT DOES NOTHING TO ADVANCE YOUR FITNESS. Thus, you won't find any repeated workouts in a Canova cycle.
4) There are two stages to preparing for a goal race. The fundamental stage and the specific stage. The fundamental stage is more interested in HOW LONG YOU SPEND RUNNING; the specific stage is more interested in HOW FAST YOU SPEND RUNNING.
Think of the fundamental stage as laying the groundwork for the specific stage. You need to prepare yourself to be able to run a progression of specific workouts based off a percentage of goal race pace. If you don't do the necessary preparations in the fundamental stage, you cannot possibly progress through the specific workouts.
Fundamental Stage
Here again the primary goal is to have you spend the necessary TIME preparing yourself for the specific workouts to come. Once you reach a maximum of time you are able to run, the focus turns toward internally sharpening that amount of time. I generally recommend building up to a 2:30-2:45 long run at a generally easy pace (about 70-80% goal marathon pace). You want to time that occur about 13 to 14 weeks out from your marathon. Then you will convert to specific workouts.
Here is how a progression of long runs might look in the fundamental stage over a 12 week time frame.
1) 90 minutes easy (70-80%).
2) 75 minutes easy moderate (80-90%).
3) 100 minute easy (70-80%).
4) 80 minutes easy moderate (80-90%).
5) 115 minutes easy (70-80%).
6) 85 minutes easy moderate (80-90%).
7) 130 minutes easy (70-80%).
8) 90 minutes easy moderate (80-90%).
9) 145 minutes easy (70-80%).
10) 95 minutes easy moderate (80-90%).
11) 160 minutes easy (70-80%).
12) 100 minutes easy moderate (80-90%).
For the shorter workouts in the fundamental phase, the same principle applies. Start on the easy side and progress the ability to hold the effort. There a multitude of approaches, I personally favor fartleks, tempos, hills and alterations.
1) 12 x (1:00 on/1:00 off)
2) 20 minutes "moderately hard" tempo
3) 8 x .25 mile hills "hard" with jog down recoveries
4) 6 x (.5 mile "moderately hard"/.5 mile "easy moderate").
5) 16 x (1:00 on/1:00 off)
6) 25 minutes "moderately hard" tempo
7) 10 x .25 mile hills "hard" with jog down recoveries
8) 7 x (.5 mile "moderately hard"/.5 mile "easy moderate").
9) 20 x (1:00 on/1:00 off)
10) 30 minutes "moderately hard" tempo
11) 12 x .25 mile hills "hard" with jog down recoveries
12) 8 x (.5 mile "moderately hard"/ .5 mile "easy moderate").
Specific Phase
Here pace takes precedence, as workouts are designed as a percentage of goal pace. Bear in mind, certain factors are going to affect your ability to complete a given workout at the prescribed pace. Rain, wind, humidity, hilly terrain, sleep, fatigue, etc. could all negatively impact your workout. You have to develop an ability to recognize this and use the sense of EFFORT developed in the Fundamental Stage to approximate as best you can the right effort needed to complete these workouts at the given paces. There is a lot of science behind the paces of Canova's specific phase but there is also a lot of art as well.
Here is a progression of Canova-inspired AEROBIC POWER workouts (~LT/Tempo/MP range). Notice how initially the duration of the repeats are shorter and faster and get EXTENDED while slightly slowing down the longer and longer they get until finally they are at essentially race pace:
1) 10 x 1/2 mile with 90 sec jogs @ 110-112% MP
2) 6 x 1 mile with 2 min jogs @ 108-109% MP
3) 4 x 2 mile with 3 min jogs @ 105-106% MP
4) 3 x 3 mile with 4 min jogs @ 103-104% MP
5) 6 mile tempo run @ 104-105% MP%
6) 2 x 4 mile with 4 min 30 sec jogs @ 102-103% MP
7) 7 mile progression tempo @ 100-106% MP
8) 2 x 5 mile with 5 min jogs @ 101-102% MP
On the opposite end of the spectrum are Canova inspired AEROBIC ENDURANCE long runs that start conservatively and converge toward race pace:
1) 18 miles incorporating 10 x (1/2 mile @ 103% MP, 1/2 mile at 90-95% MP)
2) 17-20 mile progression run from 85%-->100% MP
3) 17-20 miles with the last 5-6 miles continuous at 100% MP
4) 18 miles steady at 90-95% MP
5) 17 miles with 4 miles/3 miles/2 miles/1 mile at 100%MP with 1 mile recoveries at 90% MP
6) 17 miles with 12 mile simulation run at 100% MP
Canova is also known for very race specific workouts called SPECIAL BLOCKS. It is where you split a super compensation workout into two parts, such as:
12 mile continuous run as 6 miles at 90-95% MP, followed by 6 miles at 100% MP
2 to 3 hours later...
12 mile continuous run as 6 miles at 90-95% MP, followed by 5 x 1mi at 102% MP with 90 sec jogs
Totaling 24 miles of moderate/pace running into one day.
Again the exact workouts aren't of as much importance as the fact that you progress them. The workouts listed above are just representative examples of a progression of workouts. Bear in mind also that some of these workouts are TOUGH. They may require 3-4 days of easy running before taking on the next workout. Some (like the Special Blocks) may take even longer to recover (5-7 days). My personal recommendation is to try to maintain a consistent easy volume on recovery days (8-14 miles, in singles or doubles depending on your durability, running history, time available, etc.), and attempt workouts on days where you feel you have had enough recovery and/or you give yourself the most success to have a good workout. I also personally advocate trying to maintain at least one non-workout run a week in the 12-15 mile range, as those medium easy long runs are extra money in the bank. But that of course depends on durability, schedule, motivation, etc.