simply a tool - which must be properly used .
If anyone is looking for "one tool which tells all" ferget it
I find my 25 buck toy meter to be extremely helpful.
The prop blast on a cowled engine typically does NOT blow on the engine --unless the prop is way forward OR there is some provision for air to enter at a different angle
This is why engine mfgrs rcommend an aft opening and flow path to create a low pressure which will allow the meager "prop blast" up front to flow thru the fins and cool things.
If you look at the proximity of the engine fins to the rear of the prop -you will see no real "fan" to blow air thru the fins.
The prop blast works because it creates the low pressure that allows air to flow thru the fins .
My toy meter has helpd me solve flow problems more than once.