make sure they're loose enough that you can get your foot out of sideways but tight enough that you can't get your upper ankle shoved into it. You shouldn't look at a footstrap as a way to make your foot captive (easy to keep your foot in but hard to get it out)...look at it as something that you still have to use your foot muscles to hang into. If you ever feel the need to either reach down to open it up for your foot or if you have to wiggle your foot into it, you're doing it wrong.

One of our I20s had two footstraps on the rear of the boat - I've never felt so vulnerable than the 15 seconds I tried to sail with both feet in those straps...that was a train wreck in wait.

Also of note, the Magic Marine "light" footstraps are good in that they are more rigid than some of the others and can be set with a very large opening. We replaced the ones on our Infusion for this reason as they were an older style that wouldn't open up and stay open. I used to just barely put the ball of my toes into the old ones for safety because they wouldn't open up enough to allow escape at extreme angles. The "light" Magic Marine versions are very similar (same with different graphics I believe) that are coming on the newer Infusions/Nacras.