I have always left the PF in the brewhead when my machines were not in use. Mainly because, first thing in the morning, it is so hard to remember to lock it in place while fighting the morning, mental fog. Never caused any problems so far as I can tell. As you said, I just lightly tighten it until the pressure of the gasket stops its motion— not locked fully in place as if to brew— that saves the brewhead gasket for unnecessary compression. .