I think the optimal time to upgrade something is just after the majority, so bugs have been filed, but the maintainer is still interested.
miniblog.
Related Posts
Computing optimal 8501 instructions for rotations using an SMT solver and Racket with Rosette:
I've finally fixed an issue where difftastic wasn't showing optimal diffs if you wrapped an expression in another expression.
For example, lisp expression changes are super readable now :)
The optimal size for a hobby project seems to be medium. Big projects are more work to change. Little projects have too few opportunities for tinkering/minor refactoring.