Actually the landing power check, if you even need one (you did plan it, right?),
Planning it and having it are two different things - if you pull to the take-off limit before you commit to a high hover, you know you have what you planned for - inherently safer than flying somewhere between 6 and 8 inches (not exactly precise) below 5 Min Max and approximating that you might have enough power before discovering you haven't as the RoD builds up from your attempt at OGE hover. How difficult is it to take 5 seconds to PROVE you have the performance available?
What you do as a commercial pilot doesn't concern me, you should be old and ugly enough to deal with limited power - my concern is the PPLH like the guy in the accident who has neither the skills or experience - he doesn't have to work with razor thin margins and if he does he is likely to come unstuck. Strangely enough I am trying to help.
As for checking the performance added by each inch of MAP - just establish an OGE hover, check the MAP and add an inch to see what rate of vertical climb it gives you. You can then try 2 inches - at least then you have an idea of what sort of RoD you might be able to recover from if your OGE hover is a bit wobbly.
But I've only been flying and teaching confined area ops for 38 years day, night and NVD in singles and twins so I probably don't know what I'm talking about.