When to start increasing long run in build for >3hr marathon?
I’m training for a November marathon, targeting ~3:15 (recent HM in 1:30:31 and 5K in 19:35), and seeking advice on when to start increasing the duration of my long run.
I started NSM 12 months ago, and am currently at 7.75 hours: 3 subT (3 x 12, 5 x 6, 10 x 3), 3 easy (60 min), and LR (105 min). I plan to follow the marathon build from the book, and between now and the start of that build (~13 weeks before the marathon) I plan to increase the middle subT to 6 x 6, and increase the LR, but keep everything else the same.
Per the book, I plan to max out my LR at 3 hours, which at current easy pace would put them just under 20 miles. If I convert Sirpoc’s LR times during his marathon build to % of his race time, and apply that % to my 3:15, I would be starting the build with a LR of 2.5 hr, reach 3 hr ~8 weeks before the race, and get in 4 LR of 3 hr before the marathon.
I want to have a strong build, and am highly motivated to try for sub-3:15, but have had mixed results with higher volume (1 successful Pfitz 18/70 marathon, 1 failed Pfitz 18/70 due to injury) so want to avoid getting too high on the risk curve.
Any advice on whether the LR escalation plan above sounds reasonable, or if it should be scaled up or down in view of my goals and history?