On every type I have flown it does no harm to leave auto feather armed for the entire flight. Nothing will overheat or wear out. In fact the old RR Dart system had no pilot controlled arming switch.
If an engine fails at normal cruise power, because the throttle switch is not ‘made’ , it won’t auto feather(PT6 system, others vary).
PT6 system in cruise prop will windmill (unless gearbox or something nasty seizes).
The Pilot is then able to identify and manually feather, or simply advance the throttles and let the auto feather do its thing. Advancing both throttles ensures two things. 1. safe flight path. 2. the failed engine is not misidentified.
Switching automated systems off is generally not clever. Complicating checklists with unnecessary items is not clever either, but some operators insist on making work for the sake of it.
The old B200 cockpit is as ergonomically bad as they get, with switches easily confused until really familiar with the type and even then mistakes occur, particularly at night or under duress. A good reason to keep it simple.
Last edited by Mach E Avelli; 23rd Apr 2020 at 22:32.