want to make a “blowout” mode for the fall which would cycle through each zone with time dwells in between for the compressor to reach pressure.

Huh, never really thought about automating that. Currently I just plug my compressor into the system and flush out all the water manually.

I have some logic that holds presence in the room for different durations depending on the time of day.

I do the same and it works pretty well for areas where you usually just walk through but starts falling apart in toilets, bathrooms and the the kitchen where you usually stand/sit for a longer period without moving.