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.