Furnace & Leaks are biggest wasters of propane
In 7 years of fulltiming I can tell you that it hardly makes a difference whether you leave the 5 gallon water heater on 24/7 or just fire it off when you anticipate needing it. Water will stay warm about 6 hours after you turn the heater off. But it takes a lot more propane to heat water from 54 to 120 degrees than it does to maintain heat. My heater may turn fire off once or twice a day more often than a manually operated heater, but when it runs to maintain temperature it only runs for about 2 minutes as opposed to 5 to 7 minutes to heat a cold tank.
The new EB has the electric/gas option, but if you're using the microwave and have the fridge on electric, and the a/c fires off, and you put bread in the toaster, you might trip a breaker. If you're not dressed, it'll trip at the post!
The stove top and oven and even the refrigerator are all very frugal users of propane - but the furnace just sucks a 30# cylinder down to nothing in a couple of days.
Watching for leaks at the hoses is also very important. Sometimes event the regulator itself will go bad, but most times it's a simple fix - and as noted before - tape isn't as good a sealer as the liquid type. Figure you're going to reseal once every year or two just from travel vibration working stuff loose.
Today is a gift, that's why they call it the present.