This thread is one of those cases where you read something and realize you've been completely missing something. I don't monitor these as much as I should

Servers/services? Definitely - take your pick. Timers/jobs, particularly those on my system? Nothing!

With the right directives laid out ('Wants/Requires/Before/After'), they can be pretty robust/easily forgotten.

I've been lucky in this regard; I check 'systemctl list-timers' just to be sure - but they always run