I change my bag once a week. On those days I shower completely naked (ie without a bag). Harriet, my stoma loves the warm water running over her and it gets her really nice and clean as well as the surrounding skin. Water doesn't hurt your stoma at all - it's used to much worse :) It can't even feel the water as it hits the skin and in winter, I have some really hot showers.
If Harriet decides to 'spurt' while I'm the shower, no problems, it all goes down the drain anyway. As soon as I get out of the shower, I put a tissue over her so I don't make a mess on the bathroom floor, until I put first, an Eakin seal over her, then my one piece bag - that's all I use, no skin prep or anything (less is more!)
The rest of the week, I wear my bag. It has a cloth covering but I just hop out of the shower, pat it dry with a towel then let body heat do the rest. It only takes about 5 - 10 minutes (after I'm dressed) to dry which is nothing really.