My local IDPA club doesn't seem to assume either way. IDPA operates on a cold range so there's a dedicated safe area for loading and unloading guns. As long as you're carrying in approved position (not AIWB), you're free to "run what you brung," just make sure you're gun's cold when you step up to the line.
ETA: I'm pretty sure that most people are still unarmed when they pull into the parking lot.