I pick April 28 at 3pm.
Seriously, would love to know this if anyone has this info. I'm on the original 20lb tank over a year, but only about 8 days boondocking where the fridge was run on propane.
Don't adjust it to maximum and leave it like that as everything inside the fridge
will be rock frozen in about 36 hours or so! Adjust it according to the inside (trailer) and outside temperature. It also depends on how often you will open the door and how rapidly you close it.
As an average if no propane is used for anything else and the adjustment is in the mid range I would say at least 3-4 weeks.