I have gear that uses CR123's, AA's AAA's and A23's
I have weeded out the D cells from carry, but I sometimes carry some adapters to go from AA to C and D cell.
I dont find the multi battery type as much as a problem.
My EDC light is a SureFire E1e with the LED Head, kept in a maglight pouch on my belt with a spare 123 in the bottom of the pouch. I also have the SureFire spares carrier which holds 6 CR123's, and since buying Glowtubes I keep an A23 in the spot of the spare lamp in the centre.
I have 2 different sized battery cases made from Pelican Micro cases with different amounts of batteries that I throw in depending on what activity I am doing.
I also keep a Mini Maglight and a Solitare Maglight stashed in different kits as back up lights, so I have AAA and AA backup.
In theory it would be nice to standardize on 1 battery type, but the world doesnt seem to work that way, an this way gives me some added flexability.