If I sit down to redesign an area, usually it's when I hit hyperfocus mode and I spend hours into the night doing the bulk of the work. Once my initial inspiration train runs out, then I start going slower over the course of days. I don't know if I could ever call anything a 100% finished I'll-never-change-it-again thing. There are a number of things I'd like to try but that would create a domino effect of rearranging everything and I haven't materialized mentally where to start with that yet.
I'm a perfectionist, takes hours, and hours, and a few days later I'll tear it down again...
I've demolished my entire island many times, and now I barely touch the game, partially because my joycons have gotten horrible drift issues, all I've ever used them for is AC, have used my pro controller since the day I bought my Switch, the quality of the joycons are inexcusable.. but I don't want to play AC on the TV.