In some cases, yes. But over time the intensity of the blast comes much faster with diligent training. Like so.

[He'll demonstrate while she's charging her own blast, a simulation of solid steel walls appearing. Merely raising both his hands in front of him, he lets off a Double Galick Gun that rips through several layers with ease until slamming up against the wall, with no downtime whatsoever.]

It's as it is with anything at all. Practice makes perfect.