Having flown quad turboprops and twin piston, turboprop and jets on the 4 eng we would shut one down if we had even the slightest inkling of a problem. Better to protect the engine and save maintenance costs.
On the twins we keep em running,even if only at idle, whenever possible.
No argument about the reason for IFSD, however the data shows little to no difference in maintenance costs to repair for quads vs twins following a removal for cause.
Perhaps a pilot may be more inclined to shutdown one out of 3 engines after reaching altitude simply because he doesn't have to deal with it's symptoms and monitoring throughout the rest of the flight.