There’s no way a minuscule variation in the 0.005 seconds the ball spends on the strings has a significant impact on the opponent on its own.
Our perception of dwell time does not match what actually happens at impact. A favorable sensation may impact our confidence when hitting the ball, though. And the outgoing ball may have more or less speed, spin, height, etc. based on how stiff the string is - determined by tension, material, how much elasticity remains. But getting to the opponent faster just because it feels like it spends a fraction of a millisecond less on the strings? Not a chance.
Stiffness would be directly correlated, though, which is likely the case here: hgr isn’t super stiff but it doesn’t lose a lot of tension early in its lifespan. It stays firm enough and keeps elasticity well which allows more outgoing speed for longer lengths of time than something like ALU Power or more traditional control polys as long the racquet hits the ball with sufficient force. I experience this with HGR. Same reason I don’t use ALU to coach with. I don’t break strings hitting sparingly with most of my students, but the strings will lose tension and elasticity. Why waste ALU on that when it loses its ability to stretch so early? HGR I could teach with, as it doesn’t kill the playability for when I need to actually hit.