What's the benefit of performing regular database integrity checks? Can't we just perform it when there's a problem?
Responding to the title:
Only if you like your data to not be corrupted, or at least if you want to know as soon as possible so you can restore from backup / minimize data loss...
You could check the database for consistency after you know that there's a problem, but that's rather like washing and waxing your car after it has set on fire. The Integrity check is an early-warning and preventative maintenance step.
Make a scheduled task and move on with life.