Thanks for your responses. I've been following training plans now for several years, the latest based on Friel's book. I don't race except for the occasional time trial. I do try to set
PR's at metrics and centuries.
Following Friel's version of intervals seems to have made the biggest difference this year. Previously I don't think I did enough of them or with enough intensity. Skills work like spin-ups and ILT seem to be a contributing factor: my pedaling has become more fluid than it was.
This year my Base period went from December through mid-March; Build period through mid-April and then a peak for my first metric in mid-May. I've been through another build period and now I'm peaking for a 200k in a couple of weeks. (Again, following Friel's formulae.)
My average speed for a Zone 2 (pure aerobic) ride has jumped about 5% this year, from ~17mph to ~18. I haven't seen an increase like that in years. It feels wonderful!
I'm just trying to figure the best way to maintain those gains in the fall without burning out.