"Just leave it on...we'll control it from the truck"

[KBAustria]

Never leave control of your mike to anyone else. Turn it off when you don't need it, unless you want the whole audience to hear a private remark like "Now, what the ..."
It happens often enough when the mike is controlled by the R, it's not necessary to add further probability for mishaps
If switching the mike off produces unwanted static noise or something like that, then leave the mike in the dressing room.