I had really high hopes (and a really good first day with a 2.5hour nap) for the three nap schedule but I guess I shouldn't be surprised that it has been more of a mixed bag. Still lots of 45 minute naps even though I know DD can put herself to sleep, back to sleep and sleep longer. I really do try to roll with it and just make sure I'm giving her the best opportunity to sleep but I have to say this is what wears me down the most.
Yesterday she was up from 12:30 to bedtime at 6:00 and never really cranky but definitely tired. At least her earlier bedtime means she is getting 11 hours at night instead of 9-10 but I don't think she's quite ready for two naps just yet but who knows.
I had been trying a roughly 9am/1pm/3:30 schedule adjusted 30 min either way based on morning wake time and how long the prior nap was.
Re: 3 nap schedule = mixed bag
I'm right there with you about being worn down over this, as DS at 8 months is currently transitioning to a 2 nap schedule. This past weekend his awake times were all over the place, and I'm finding that he's not giving as many cues as he used to, which is making it even harder.
From ~4 months to about last weekend, we were able to maintain a really consistent 3 nap schedule by putting him down about 2.5-3 hours following wakeup (usually around 6 a.m.), and then never allowing his awake time to be more than 2 hours for the rest of the day, regardless of how long his naps were.