Does it matter?
This is one of those questions where everyone will have their own view, and at the end of the day they are probably all correct in the right circumstances.
Of course there are times when it is important to climb at best rate, or best angle, for terrain clearance. But if terrain is not an issue, you can climb at pretty well whatever speed you want. Some will go for best rate, some will prefer to lower the nose to give better visibility and improved engine cooling. Personally, I don't care.
However, what is important is that you decide what it is you're going to do and why you're going to do it. Deciding that, due to a combination of engine cooling characteristics, excess performance and the terrain on the climb-out, you're going to climb at Vy+20 is absolutely fine. However, getting airbourne without having thought about a plan or a profile and settling down to a speed of Vy+20 because it seems about right is not ok.
Personally, I usually follow my company's standard procedures, which call for a climb at 100kt (Vy=85, so that's Vy+15) and at a reduced power setting. However, there are times when this won't achieve the required climb gradient (usually an ATC climb gradient to comply with a Standard Instrument Departure, rather than terrain, but the principle is the same), in which case I will quite happilly climb for as long as necessary at Vy and at full power (which happens to be allowed by the POH for my aircraft, but isn't for all aircraft).
FFF
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