TiZ question for blocks

I use TR as a training platform but don’t really follow the plans (because I don’t race). I use AiFTP detection (because testing is the worst), but mostly try to follow a base → build reciprocal training pattern this year (I did follow the plans the first few months of 2022, but then I had COVID, I had to miss my trip, so using plan builder doesn’t really make sense).

I do sweet spot blocks, then VO2, then FTP. 2 hard workouts per week - rest Z2 or Z1 commuting. I try to push time in zone - so start with 3x15 SST, then 2x20, 2x25, etc… (same for FTP work).

My FTP bumps these days are 1-2 watts (so not really anything more than power meter variance or error). My question is when I start a new sweet spot or FTP block and my FTP is within 5-8 watts of when I did that type of block previously, should I restart at 3x15 minutes SST, or pick up from where I left off 3 blocks further.

Example - I just finished a SST block and made it up to a 40 minute sustained SST effort at 90% followed by 85/100 over unders (2’:1’ - so they average 90%, 3x9 minute in total). When I get back to my next sweet spot block do I start attempting 1x45? Or go back to 3x15, 2x20, etc… If I have some miraculous FTP bump than obviously I would restart with shorter time in zone, but if it stays within 1-2% of my current FTP should I just keep the progression going (even though I last did a long SST effort 3 months prior).