You don't say which housing you are using and that could make a difference. Some folk, when on a dive trip, seem to grease their o rings all the time. I think that is asking for trouble. If I know I am leaving for a trip, I grease the o rings with a very light coating of L & M o ring grease. I do not grease them again until after I have arrived home. I use a lintless cloth diaper or hospital blood cloth to remove any extra grease. That doesn't mean that I don't give them a good eyeball inspection each time I open the housing to switch batteries or tapes. Look for lint, hair or anything that may prevent proper sealing. Taking them out of their groves and putting them back in after each day is just unnecessary and adds wear and tear on the rings. I use a broken credit card to get them out, never a dental pic as I have seen others use. Of course, once my trip is done I soak the heck out of everything in warm water to remove any salt residue. That takes care of the buttons on my L & M housing as well. I definitely avoid using a high pressure nostle off a tank to blow moisture off the housing. If you are not careful you can dislodge an o ring or actually blow moisture into the seat.
Hope some of this helps-Steve:14: