As a preschooler, DS had a busy schedule with very little downtime during the week. He has special education preschool in the mornings. He had some activity every afternoon: speech, OT, a therapeutic movement class, or swim class. Additionally we did 3-4 hours a day of our home ABA/VB program. He did get a "nap/quiet time" in the afternoon and he had a little bit of downtime in the evenings. Also he had more unstructured time during the weekends. A lot of people criticized us for putting such a young child on such a heavy schedule, but we felt all of it was important to help him gain the skills he needed.
His schedule got a little lighter once he started kindergarten. Partly because because we dropped the daily ABA/VB sessions (his classroom used the TEACCH methodology and we wanted to avoid confusion). And partly because I went back to work full time and DH was a (involuntary) SAHD. DH took DS to his therapies and classes, but didn't structure the at-home time as much as I did.
I agree with Catherine that you need to find a balance that works for your child and family.
Gena
DS, age 11 and always amazing
“Autistics are the ultimate square pegs, and the problem with pounding a square peg into a round hole is not that the hammering is hard work. It's that you're destroying the peg." - Paul Collins, Not Even Wrong