When I used Speedplays I was a fanatic about using the covers. OK so they fell off once in a while but without them, I would get dirt or worse in the cleats and then the cleats were useless. I did almost a whole century (Tour De Tucson) not being able to engage my pedals because 1) I forgot my covers and 2) after the first "water" crossing (those that have done this ride know what I mean) the cleat got dirty and I getting engage the pedal. Talk about really sore feet after!

Speedplay folks - get covers. You will thank me later!