I got commissioned thru ROTC in 1990. I had a 8 year ADSC letter.
A few months later they sent us a new letter forcing us to sign a 10 year ADSC letter if we wanted to go to UPT.
A few months later they sent us a new letter changing back to the 8 year ADSC.

Rumor Begin....Supposedly, the 10 year ADSC violated some Indentured Servitude Law from back in the 18th Century!
Congress had to remove that law for the 10 year ADSC to come into play?....Rumor End

I talked to an AFPC leader about this being an awful large committment for a 21 year old to make.
He said "We will never run out of the demographic of young men who want to fly jets in the Military. What we run out of is 30 year old men who aren't burnt out!"

The 10 year ADSC after UPT wings is their way of getting you over the half-way point. Hoping that a higher percentage will want to stay for 20...If it meets the "Needs of the AF"