I think I'll do 20s for the first 6 weeks (the endurance mesocycle) as the long runs there are proceeded by an easy 5 and followed by a rest day. After that I'll stick to the plan.
I've done just over 1,000 miles this year. Currently 64 miles over an 8 day rotation with two 8 or 9mile speedwork sessions, a medium long 12 and long 20, sandwiched between easy 5s and a rest day. (Works out 56 miles a week long term)
I'm due to start a P&D 55-70 in June for an October marathon. I've been running a 20miler every 8 days for the last few weeks, so was thinking of swapping the P&D's scheduled long run for a 20 each week.
Is that sensible, or should I stick to their plan?