I joined a running club that has a coach and a large group of people who are focused on 1 spring marathon and 1 fall marathon. I tweaked the training because it called for too intense sessions more frequently than my body could handle.
I also think I did not quite reach my potential even when training well because I let my social life cut in to my recovery too often and it caused unnecessary setbacks. For example, I went to 4 weddings and 3 bachelor parties during the buildup to my Marathon PR. Running a hard long session after 10+ drinks and 6 hours of broken sleep takes a toll on a 30+ year old.
The schedule for the club plan was workouts on Tuesday (usually Threshold reps or something more V02 max based) and Saturday (more marathon specific) with a LR on Sunday and occasionally a short workout on Thursday. I found that to be too many days with intensity for me and it left me burnt out. What ended up working best for me was the following:
Monday: easy run in Am + speed development PM
Tuesday: workout with club usually something between 1k-2mile repeats between 4-8 miles worth of work depending on the stage of the training block
Wed: Medium long (90-105minutes)
Thursday: recovery either 2 30-35 minute runs or 1 60-70 minute run (very easy pace)
Friday: same as Thursday but add strides
Saturday: Long Run w/marathon specific workout included (i.e. 20 miles with first 5 easy then 3x3mile @MP, 1 mile float in between, 4 mile cooldown or 20 miles with the last 6@Mp). This all built in duration of MP work over the course of the buildup and I had one LR every 3 weeks that was just easy pace although I often did it on hilly trails.
Sun: off or 30-45 minutes very easy.
In my best buildups I raced relatively frequently too on race weeks I would adjust and replace my big Saturday LR/workout with a race day and long cooldown. I raced at distances from 5k (both XC and road) to Half Marathon. Before my Marathon PR I raced 6 times during a 14 week build, including a Half Marathon PR 22 days prior to my Marathon PR.
This is what seemed to work for me short term. I improved consistently for 2 years straight but have stagnated or regressed since then. I am still working to find a way to take the next step but will have to wait a little while because my wife and I have a newborn and childcare plus my full time job doesn't leave much room for running.