Our Air Force checklist says it will be in ALT when entering an active runway and STBY after exiting the active runway, so that's what we do and that is the same thing I have always done civilian flying. I will turn it to ATL on the ground if I am at one of the 35 ASDE-X airports. At the other 15,000 airfields in the country, I will continue to leave it on STBY on the ground.
For Joe Cessna flying into Podunk Airport in the middle of Nebraska, having the transponder on ALT literally does absolutely nothing to benefit him. The only thing it could POTENTIALLY do is cause his airplane to show up on TIS/TCAS(had it happen and we don't have "outdated" avionics). Yeah it doesn't give a RA but the target still shows up. Heck, ships in the harbor around Norfolk show up. So I'd say with it needing to really be on at 35 out of 15,000 airfields, I will stick to doing my normal routine of putting it in STBY on the ground.
In a nutshell:
1. It isn't regulatory
2. If you don't have it in ALT at an ASDE-X airport, the worst that is gonna happen is ground tells you to turn it on. No big deal.
3. I can't believe I am typing this long of post about something so minuscule as the transponder being in STBY or ALT on the ground.