The 21-year old joined the Dutch Eredivisie outfit from Villarreal in the summer and has settled well, scoring three league goals in eight appearances, along with four in the Europa League (including qualifying).
Altidore is now becoming a first choice for US coach Juergen Klinsmann and he puts it down to plenty of minutes with Alkmaar.
"It's been huge. It's important for any player, because that's when you're at your sharpest, when you're playing all the time," he said.
"Always being in gamelike situations is important; for me it's no different. I'm really glad I get to do that.
"Playing, that's the biggest thing, and I'm getting that there. And not only that, but playing at a pretty good level against good teams.
"You've got the Europa League as well, playing against good competition. So for me, it's important. I feel more confident on the pitch now, I feel fitter, I feel stronger.
"I think that all accounts to the playing time I'm getting.''