[Lizard]

You probably don't want to set both the project and the stuff in it to repeat. Either one or the other.
Suppose you have a "Clean House" project with "clean counters" and "sweep floors" in it, and want to do each of these tasks once a week.
If you tell the project to repeat weekly, then each Saturday morning, the project will become due, you check off each task in it and then check off the whole project and the project will create a fresh copy of itself due next Saturday (with all the actions in it waiting to be checked off).
If you tell each action to repeat weekly, then you'll only ever have the one project and you'll never check it off ("a woman's work is never done"?) but you can check off each task in it independently. Check off "sweep floors" on Tuesday and (if it's set to repeat on completion date) it will reappear next Tuesday, but the "clean counters" will reappear a week after you check it off on Thursday.

If that's still not making sense, try asking again or provide an example of what you're trying to do.