In 120, I keep four A12 backs loaded and always ready to go (each is stored double zip-locked in the refrigerator compartment labelled "butter"). Two of the A12s are (currently, until my stash is exhausted) loaded with E100G/VS; two others are always loaded (depending upon the season) with either PanF Plus or FP4 Plus.

In 35mm, I generally have film loaded in at least four or five bodies: My F6 will have E100G; an F5 will have E100VS; an F3HP or an F2 will have Tri-X/HP5 Plus; and one of my M6s will have Tri-X/HP5 Plus while the other will be loaded with PanF Plus.