Sounds preposterous, like training to eat. But I plan a 3 100kms trip next spring on a tight schedule that won't give me any zero day if I ride my usual average of 100kms/day. Coincidentally I've purchased an entry-level trainer so I plan to try to improve my power.

1. I've raised my cadence from a 65 rpm baseline, up to the more generally recommended 80+. Faster cadence means less resistance for a given power level, which is probably desirable since I am not a strong rider.
2. I've attempted a spur-of-the-moment ramping-up FTP test, rather inconclusive because I couldn't keep up during the last 2 segments. Results suggest 205W. I comfortably push 135-150W in zone 2 HR (endurance) for 30 mins. (just starting...)
3. I have 2+ months before I can ride outdoors in reasonable weather. Current objective is to increase endurance power in the 150-180W range, which would be a considerable improvement over last year where the few data points I have suggest a sustained power of less than 100W over 6hrs.

I've read ACA's guidelines. Very general and apparently targeted at less experienced riders considering a rather leisurely 2-week summer tour. I've also read training guidelines for randonneurs, but brevets/audax being shorter and more intense than what I plan, I am ambivalent. I've also read training guidelnes for events like RAAM -- I might as well have read about the Tour de France. Way above my pay grade; overly ambitious for what I am planning to do.

So, in very concrete terms, I plan to ride 50-55 mins 5 days/week at HR 115bpm (upper limit of zone 2 in my case) at a cadence of 80-85 rpm, hoping to see power creeping up. I'll also perform a ramping-up FTP test on Fridays to tracks eventual improvements.

If someone in this community has expertise to share, I'll be happy to learn.