There isn't any right answer to this debate...
I never got to hit up training mode when I was in L.A. last week so I never really went for any hyper drive combos but I can say that I was the ONLY person in the house on Friday to beat Mr. KOF (Even if it was only once) :D . I went for BnBs and the occasional simple DC (ex. Ryo DP -> DC -> Ranbu). At the end of the match my Terry had 4 stocks and a full HD bar but the way I finished it was an outside-of-combo EX Bustah Wolf so you just never know what will actually get the W. At the end of the day there will never be a strategy that is all-encompassing and covers every single situation so HD combos are practical, DC combos are practical, EVERYTHING is practical because it all goes towards conditioning and even a seemingly lame strategy can come out of left field and trip out great players.
I don't mean to burst your bubble but he was messing around trying get enough meter to try stuff. I think I must've saw him do like 5 uppercut whiffs on purpose to build his gauge.
To add to that, you weren't the only one who beat him that day, I among other people did as well (you were just watching some other game with Trevor). Otherwise, he'd have a 40+ streak if he only lost once then.
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I'm too for the there's-no-right-answer train. Different strategies, different opponents, different characters, too many variables.
Like Ash said before, Chin does real good damage with just a drive cancel and so I don't usually save up to HD. Shen on the other hand has good combos all around: tons of non cancel combos, several good ones that do 50%+ dmg with
one cancel and
one stock but to spend any more than 1 cancel for Shen is
almost always a waste --> Save for hyperdrive. He simply does too much damage even if he doesn't have much stock but full HD.
To top it off, you can BC bypass by performing his Ex Command Grab with hcb~f+ABC which setups up a bunch of combos.
In contrast, Maxima isn't really a HD kinda person, I rather use two 50%+
one cancel two stock combo coz they're relatively easy to land.
It just depends.