Comment # 18 on bug 1124823 from Lukas Ocilka

(In reply to ravas mi from comment #13)
> Then I guess I would setup a popup to activate an hour after boot, and ask
> if it's a convenient time to perform disk maintenance. "It has been <X
> amount of time> since the disk maintenance script ran: Would you like to run
> it now?" With options to remind me in 1 hour, day, or week.

There's no good place/time/way to display such a pop-up. Remember: Systems
are to serve, not to bother. For that reason, systems can run without any
user interaction (headless) or with several different display managers or
even without GUI, just with text-mode.

FS maintenance (if really needed) should be called when the system is actually 
idle. If it's idle, it often means there's nobody reading any pop-ups and
nobody can answer such question.

And BTW cron is ideally replaced with systemd-timer(s)
https://www.freedesktop.org/software/systemd/man/systemd.timer.html