My experience I feed over 200 live prey each month just to my breeders (that's well over 20000 live feeders during the last decade, during hatching season add 300 to 400 more a month), in those years I never used a piece of dog food in the enclosure and also have never had a single issue. I breed my own rats know they are well fed and well hydrated and it has been my experience that if not snatched out before hitting the enclosure's floor the rats will simply go in a corner where they will usually fall asleep.
As for the killer rats out there it's greatly exaggerated by pro F/T feeders people with an agenda and ZERO experience that continue to propagate the myth of the killer rat rather than educate people on how to properly feed live. The pictures and the tales all have a back story that does not represent live responsible feeding
As for the question if that makes the OP feel better why not there is no harm in doing so but for a feeder that should remain in the enclosure no longer than 10 min I find it unnecessary.
Just myand some change