I've never seen a long-time perm
BC of any svc get stuck to driving only 1 bus model throughout his
entire span of time on 1 svc. Esp those who can drive DDs typically
alternate between SDs & DDs. Even if you're talking about KUBs,
there's different versions. And that's not including yet the random
BC cameos, whereby they drive buses on svcs other than the svcs
they (the BCs) are usually perm on.
And even if they're bored, the
bus isn't theirs. Some of the more senior BCs of each svc might get
some special privileges to drive certain specific buses each day,
but at the end of the day, the buses aren't their own, it's the
company's (whichever TT/GA/SBST/SMRT company that is). They drive
what they're assigned to.
Even if that entire svc is made up of, eg, all Citaros, it's still
their job. no choice, suck it up and drive what they're
assigned.
I remember last time TIB932T SL always drive Lance on 961 until
the day all Lance died, he drove Lance only until OC/MAN took over
the shift.