Matt,
Basically the longer your air system holds air without being replenished the better given it has fewer seepage points. In a practical sense there is a broad range of normal lasting days to weeks before the coach settles and is no longer supported by full air springs.
If your coach has air brakes you can do a search on air brake leak down tests. There is a routine you should learn that involves applying the air brakes, holding the pedal down for an extended period of time (1-2 minutes) with full pressure in the tanks, engine off, looking for a leak down rate of around 4lbs or less. The parking brake should be off during this test. This will tell you if the main air system and brake system is acceptable from a leak point of view. There are two needles on the air gauge, red and green, the front and rear brakes are isolated systems and one needle represents the front system and the other the rear system. The air suspension uses one of these reservoirs. There should also be no leak down of significance with the parking brake off, ignition on, engine off, foot brake off, as a separate test. This checks the air diaphragms of the rear brakes that compresses the rear brake springs.
I cannot speak for your particular coach model, how long is normal for the coach to maintain full air springs, but I would guess that it should be days and not hours. Someone else who owns a similar coach may want to chime in on their experience. Keep in mind that being under one of these coaches is dangerous. It is being supported by air and if a leak was to occur while poking around the air suspension components the coach could come down and injure you or worse. The frame should be blocked as a back up when under there. Hope this helps.
Later Ed
