I went from 6 1/8 BPEL to 6 5/8 when I started, then fell off completely for 3 years. I only lost 1/8, going back down to 6.5. I remember it felt like I was stuck at 6.5 forever because my noobie gains spoiled me. I’m guessing that the time I spent straining at 6.5 BPEL at the end of that cycle helped cement most of those gains. Either way, almost all of my gains definitely cemented somehow.
Three years later, I returned and sprinted from 6.5 to 7.0 in a year or less before slogging a bit to get that last 1/8th putting me at my current 7 1/8 BPEL. So 3 years definitely restored my tissue to a noobie state. The gains (.5 BPEL) and point where the gains slowed (the last 1/8th) were identical for both cycles.
I’m currently restarting manuals after a 4 month flakeout/decon and eager to see what that little vacation nets me. For me, decons seem to be a slow but guaranteed source of gains. I just need to dial in what sub-3 year length of time off gives me that tissue reset.