Chiming in on the “no more than 3 hours” training topic…
As a 6-7 hour marathoner, stopping at 3 hours sounded nuts to me. Only train up to less than HALF of the race distance??? And while doing Dopey, nonetheless?! I had always topped out around 5 hours in training for my longest runs, and did at least 2 b2b2b2b weekends for Dopey with the final one being a 3/6/12/20 mile stack. Never injured (at least not from training or running - I did manage to break a toe whilst making the bed once), always successfully completed my races feeling good (I mean, relatively - there’s always a point in a marathon where one doesn’t feel great, right?!).
That said, training for my final marathon was interrupted by health issues and my longest training run wound up being 16 miles, a little under 4 hours… I was surprised to find that I had no issues with endurance during the race. The only major problem was some IT Band pain, which always rears its head if I take a massive jump in mileage - that set in around mile 20, which makes sense. But I finished and other than the angry IT Band, I felt solid.
BUT. That was my 7th marathon in as many years, 4 of them during Dopey: I am 100% convinced that I got away with being “undertrained” because I had a decade of long distance training under me already. I think that’s something we don’t talk about enough - the cumulative effect of years of long distance running. You build strength and endurance through that that doesn't just drop off a cliff, right? And you build mental strength through those years of training, too. No question that I was able to draw on all of that for marathon #7, but I really do not think the same would have been true for marathon #1, had I only trained up to 3 hours. I remain skeptical of the no more than 3 hours “rule” applying to everyone, but can now see how it can apply to some: as always, we are all an experiment of one.