I would definitely agree with turning them off when not in use. That just eliminates a potential failure of the regulator or lines as a possible cause of either fire or just leaking your gas away. Rarely would you have a problem with a reg in good condition, but this is just extra insurance.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.