I believe it depends on the school. However, I would not worry about it. Let's say your tech school is a yr.
Arrive at school Oct 1, 2017 (EAD) - release 2021
vs
Arrive at Operational base Oct 1, 2018 -release 2022.
You decide to TA and finish your masters 2019. Either way you are stuck until 2022.
Go with no extra commitment for tech school. However, the AF sends you to Lakenheath. That is a 3 yr tour, PCSing in 2020, but due to timing you are not in the 365 day window, so now they PCS you to Pope. You want to end up in Oregon. You can't non-vol since you are not within the 365 days, and now you have to take that Pope assignment, which adds on more years.
I could do this all day long on how even if the school is 1 yr they can keep grabbing you. If you truly want to be out as fast as you can, than you really need to plot your career. There are many that do leave at 4 yrs ADAF, but impho there are a lot more that have to stick it out because either their PCS did not align or they took TA for their Masters.
~ Heck Bullet served 21 1/2 yrs because we had to PCS at 18 1/2 and that incurred a 3 yr committment.