A 10 year old novice will catch on a lot faster then a 4 or 5 year old novice. I think 2 years is reasonable for the young ones. Top of 8 and up should't need more then a year.
My first boy (Mark) was a first year novice on the bottom of 6 and under. He went to 7 tournaments and got 1st place 4 times, 2nd place once, and 4th at the Championships. Clearly we didn't think he needed another year in novice but some people did.
My next son (Max) will start novice next year and i think he will need 2 years in novice. Some kids have it and some don't. Bottom of 8 on down need 2 years.

Mark Butcher