I used to use root's crontab(1) even for things specific to my regular user. I didn't know that each user can have their own.

Comparing to the root's /etc/crontab we do not need to specify as "who" the command should be run.

crontab -e

#minute	hour	mday	month	wday	command
0	*	*	*	*	echo "do stuff every hour"