Speaking of mouthpieces that are kept in gigbags
(attempt to keep "on-topic"), I used to work for (quite a lot, come to think of it) a banjo/guitar player/contractor who kept, in the trunk of his car, one each of the "standard" sized brass mouthpieces (trumpet, trombone, tuba), just in case someone showed up to one of
his gigs without one.
I can attest to the fact that they were occasionally used......

"Even a broken clock is right twice a day".