Basically three runs per week(track interval, tempo/race pace, long run) and two(or three) cross training workouts. All runs are at pretty high intensities.
Yes. Ran my first marathon using the plan with moderate success. I was able to quickly improve my running speed and endurance, but ended up with an IT band issue. My guess is it was from too much intensity. 3 hard runs a week were too much for me. I’m currently using a modified version of the plan, 1 track workout, 1 tempo run (both at FIRST based paces) then a long run at whatever pace I feel like that day. I swim, bike or both on the other days or add a nice 3-5 mile easy run. So far seems to be working and I feel more healthy this time around. My 2 cents.
PS - was training for a 3:15, ended up running a 3:19 injured, so something worked.
I just used FIRST for BQ effort. Thought hard runs were hard, but enjoyed only running every other day. Did some swimming and biking on off days. Worked well for me because I already had monster base built up. Would not want to try FIRST without monster base already in place.