Clones, with two exceptions, grow at double the rate of other humans, by design to have a large batch of adults in 10 years.
Seems like they wouldn’t be able to grow very many clones in 4 years. Don’t they say in AOTC that the army was 200,000 strong with 1 million on the way?
For some reason I thought they’d established there were 5 years between AOTC and ROTS.
I just checked on Wookieepedia and Sifo Dyas was killed exactly 10 years before the start of the clone wars, so by the time of AOTC the oldest clones would be about ten years old, i.e. the equivalent of a human in his early twenties. So it makes sense that they’d have a bunch of teenagers almost ready to become soldiers at this time. And of course we see a lot of clone children in both AOTC and TCW, as well as in The Bad Batch.