Timestamp and crons are meant to be used for completely different things.
If you're counting down something in minutes, say a reset timer then a timestamp would be the better option.
Where as (like you've said) something like an automated backup would be done through a cron. Crons are meant to be used for scheduled events, just in McCodes someone decided to count down minutes using the crontab (bad bad idea).
http://en.wikipedia.org/wiki/Cron