Ok, my turn to clarify a post....
My query on oil cooler fan was not meant in any way as an aid to reduce #8 brg coking, just a bit of thread drift....
Me personally, I switch the battery off once the blades have stopped, regardless of fan operation.
MT - Those temp's/times and a chart you mention are interesting. I have seen a chart on the RR250 series where the core wheel temps have stabilised and plateau after 1 min 45 secs but BHT round it up to 2 min 'cool down', but do not recall any raising of core temps by going past that.