I leave mine plugged in. But note that some folks report that the NEMA 14-50 receptacle is not rated for lots of connect-disconnect cycles. Thus I purchased a 2nd UMC NEMA 14-50 adapter which I keep in the UMC tote bag. If I need to, I disconnect the UMC at the adapter (and do not disconnect the 14-50 adapter from the wall). Thus I do not overuse the receptacle, and am not worried about failure. Of course this is a bit of overkill since a new receptacle is about $10-15, but did not want to run into the overheating/meltdown scenario occasionally noted here. I suppsoe that the connection between the UMC and adapters can fail too, so who knows what is really better.