I don't know if this is somehow particular to my setup, but on both macOS and Linux I find that simply running full `compinit` fails to update mtime on `~/.zcompdump` when nothing's changed. That causes this optimization to fail, for me, if my completions haven't changed within the last day.

This is fixed by adding an explicit `touch ~/.zcompdump` in the branch that runs a full `compinit`.