A battle perhaps. Less so if say, Asahi has to get there. Combat and running long distances are both just as intensive in the suit, granted one is less lethal then the other.

While I know their powers can't compare, I gave Asahi's armor a hard one hour limit for much the same reason All Might has roughly three hours (or less) on his: it's so that it can't be inside of it all the time. The power is going to be used regardless if Asahi is active or idle in his suit, so he can't just waste time standing around doing nothing for most of it. 

And if I go with your suggestion that the power drains if he's more active, then hobble his time to thirty minutes, against a foe that Asahi can't overpower immediately (which is a lot more then you'd think since the Guardian One isn't made for big damage), he'll last maybe ten minutes against a foe he can't defeat. And that's assuming he didn't already use up most of his power just getting to the fight, like if he is on patrol through the city during a class lesson or something.

Kinda hard to be the party tank when you're only useful for about ten minutes.its about as bad as Deku's One for All except Asahi doesn't break his limbs everything he dons the suit. and the Guardian One isn't nearly as powerful as Deku's One For All when it's in use either. The Guardian One is made for endurance, and ideally it does a good job at it.