I leave my two traillers connected to 120VAC Shore power connection to my GARAGE 20AMP Receptacles using the RV30A-15A long adapters.
This allows my smart mode converter/chargers in both trailers to keep my batteries topped off.
I also occasionally check my batteries fluid levels.
Before I replaced my older single mode converter/charger with a PD9260C I lost one of my batteries from boiling out the fluids and shorted out a couple of cells.
Since using the smart mode converter/chargers now I still occasionally check my batteries for low fluid levels but never see that anymore.
During the winter months where cold weather is much harder on my batteries I definitely check the fluid levels more often but all seems to work just fine leaving my batteries connected to all the time...
Roy Ken