Our main base & company had been involved in the
BETA programme. Prior to that, SOPs and practice was to (de)select STBY when entering / exiting RWY. Then we were asked to keep'em on for taxi. Given the fact (single hub ops) that 50% of our movements were in this environment, it found its way to SOPs. Of course, only after was confirmed that the installations are correct and modes A,C would not misbehave on ground, also this makes sure we do not fuss at other airports.
I turn the anticollision light on before pushback and select TA/RA on the squawkbox in sequence. Similar applies for shutdown. Unless one gets distrupted enough to omit, but then that's what checklist are for.
Note: the boxes have neither "OFF" pos, nor "S". Our installations come with "TEST, STBY, ON, ALT RPTG OFF, TA only, TA/RA" along a dial selector. Given the pinpoint description provided above, it is pretty much evident what they are for without further explanation. Air/ground logic provides for proper behaviour on ground.
Cheers,
FD.