If you shoot with a model more than once, do you have them sign a release for every shoot?

yes! Each release is dated .. the pictures that are released are those pretaining to the date the release is signed!

I usually sign a different release [oh well, just the date changes] for every single shoot. I think it's the best way.

Delilah

Yes.

Absolutely. Technically, a model release is only legally valid for a specific shoot, which is why the form is dated. Just because a model signs a release for me to use photos from a shoot I did today, does not mean they are signing away rights for all future shoots without any further releases.

In an extreme example, I once did a photo shoot in studio with a male model, and he signed a model release. Later that same evening, we were both at an opening event of a new clothing store, and I shot a few more snapshots of him there. Had I wanted to use those photos from the event for commercial purposes, I would have needed a second model release from him on the SAME DAY, because the first model release did not cover the circumstances of the later event, only the initial photo shoot.