I think I've read they maybe grow a foot a year.

Depends on MANY factors. In a tightly controlled environment such as a nursery pot, where you can control rootball size (pot size), water, and fertilizer, you could get 3'-4'+ of growth. The hard part of pushing them that hard is the new growth may not harden off completely. A foot of growth would be for a reasonably healthy landscape tree in a lawn without extra watering and fairly nutrient poor soil. Stressed trees would grow less but most young Sugar Maples would do 1'-2', occasionally more in ideal locations.

without mycorhizzae and fertilizer arlund 1-2 ft. with it, much much faster growth, like 4-7 ft a year