I once spent 6 months leading up to summer to plan out a campaign that would take us 3 months to get through, and while I allowed the team to do whatever they wanted, let's just say a few villages grew legs to plop down ahead of their path. Not everything was planned, but the bulk of it was there and details could be filled in as we go and they become relevant. Always keep notes.
Then one day, one of the players couldn't make it, so we still met but with 5 instead of 6. Nobody wanted to play without 6, so they asked me to pull out a side one if I had one. I did not.
So improvisation it is.
Afterward they asked if they could restart and play THIS campaign instead because they felt I had put more thought into it than the previous one.
I'm gonna be honest, I finished the campaign but that comment killed my passion for it because they essentially told me "your plans are shit, we'd rather just have rehashed tired movie plots instead"
It's been years and my dice still sit on my shelf, notebooks boxed up I don't even know where. I don't think any of my character sheets survived my last move either.
I guess I don't have a point beyond reminiscing