Who's just talking about pistons? Turboprops fit in the lightie category for certification ie FAR23. I flew a Cheyenne 1 the other day. PT6s can have a failure that causes a massive power increase on the affected engine. In that instance, 'dead foot, dead engine' is also likely to be 'dead pilot'.
Anyway, a failed engine isn't necessarily the clean stop, black & white process that tends to be what happens in training. A surging, rough running piston engine also needs gauges to be checked. Not just for the suspected problem, but also to find the *good* engine . Random (or semi-random) yawing back & forth isn't really amenable to a simple 'dead foot, dead engine' philosophy. You can find yourself dancing on the rudder pedals to hold a heading.
As for confirming what you already 'know': Better would be '...what you *suspect*'. Lots of accidents where the pilot made the information available fit his or her preconception. It's important to look for contradictory evidence too.