Our smallest of 3 student loans was 24k. We have been able to put 800-1900 (edit- 800-1900 per month!) towards it with my variable income, as well as paying $600 a month on other student loan minimum payments.
In December, even with Christmas and travel to see family (which we saved for during the year) we were able to put 2/3 of our month's income towards paying off the loan. I got extra shifts and sold some extra things at local markets plus a few nice Christmas bonuses. $1000 in early December, and today after taking what's left over, another $2500 from December!
There's now just a few hundred dollars left and it will be gone later this month!