Stupid PAM question

I know PAM is suppose to be good for a few weeks. I change my cages every week (more often if they need it). There is always one cage that my dear snake has tipped over his/her water bowel. I take it I have to retreat the cage before I put my snake back in so the PAM is working right? The water will wash off the PAM right? I just wanted to make sure. I am rotating cages so I can just switch cages. Out of the dirty, into a clean one in just seconds. Man that makes life easier.

I got a few cans of it because I wanted to have something that really worked on mites. I have not seen mites on any of my girls, but one boy (in quarantine) had one on him last week. He is separated from the girls but I want to be safe. I change all cages the same. I take out the snake and put him/her in a clean cage that was treated with PAM a few days ago after I cleaned it. So the cages have been stored for a few days so the PAM is good and dry and no fumes remain. The boy in QT all his stuff is cleaned the same way but is stored and cleaned not only in a different location but on a different day. Is it ok to spray the PAM and wait a few days (up to a week) before I put the snake in the treated cage? I am making sure that all my snakes are in treated cages. Is that overkill and will it hurt my snakes? Thanks and sorry for the long post.