I usually keep all my 'stuff' in the car in a hollister 'purse.' 2x flanges, 2x bags, sissors, paste, powder, spray, glue remover and 4x of those small tissue packets. When I do change my flange/bag, I take them from this purse, so they are always being rotated out. The longest they stay in there is 14 days. Never had a problem with flange deterioration or anything, and they're out there in the heat or in the cold...doesn't seem to effect them IMO.
Besides the stuff in the car, I normally don't carry any supplies on my person. I'm hardly ever more then a 5-10minute walk from the car anyways. Probably just as far as the nearest washroom. When I *do* go for long extended periods from the car I'll take a precut flange and bag with me, just in case, but that's it. It's just to get me back to the car and my other supplies.
Dec 2006: Proctocolectomy/permanent ileostomy
Since 1991: Indeterminate crohn's/ulserative colitis