The first year of the pool I did a backwash at 6 months, and a full disassemble clean out at a year. Given the unwieldy process of the backwash and "that should be good" precision of adding DE back in, I decided to just skip the backwash and do the full clean out when the PSI got 25% over the starting PSI.
Problem is, it's a year later now, and the PSI is maybe 10% above clean. The water features don't quite have the oomph of last year, but a few adjustments to valve splits or VSP speed and it's fine.
Is it still worth it to do a full disassemble? In some ways I think the fewer times I take the thing apart over the next 20 years, the better chance it will last (lost parts, misaligned assembly, dumb accidents). Water is clear, and turning the light on the other night, the normal number of floaties.
I suppose the other option is that the PSI gauge is not reliable?