Ours has one near the door as you enter. Makes it nice to shut down the small discharges if we aren't going to use the camper. Now with solar it's not a big deal but typically if it's going to be more than a day or two I will shut down solar panel production and turn off the battery bank. No need to have active circuits when they aren't being used.
In our new camper I am installing one of these at the battery box
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It's handy to be able to shut down the battery at the source and de-energize everything past the switch to work on either the batteries or the camper.