to do recalc by cron. how often?

Hi

It would be great to have recalc running by cron or by scheduler (e.g. in night).

I have 130 groups, and a few new nodes and comments for them for a day
Will be safe to run it once a day? or few times for a day?
I absolutely have no idea about har hard it is for a system. Moshe wrote something that it can be really tough to database.

or it is ok to run recalc only once when I enable this module and then to run once a day something to update statistics in this module.

thanks for your opinon
Igor