I was an Army brat growing up and joined the Army Reserves right out of high school. I was also in Army ROTC in college but dropped the last semester for a Navy AOCS slot. I originally had a waiver for my eye-sight to be a helo pilot, but than got a new adviser in ROTC the fall of my senior year. Before he killed himself to keep from being arrested for raping and murdering a female ROTC cadet, my adviser managed to get my helo waiver pulled and my commission changed from a Regular Army in Armor (who flew the attack helos back than) to a Reserve commission in the Medical Service Corps. Yup, you guessed it, he didn't like me. More precisely, he did not like any Cadet who had a Dad that was a senior Army officer. Besides the girl he killed, there were 6 or 7 of us that he screwed with. The LTC in charge of the ROTC was worthless and did not care.
So after he killed himself, I had already graduated and was waiting to start AOCS. The Army Inspector General completed their investigation of the ROTC unit (the LTC was relieved and retired for lack of leadership) and sent me a letter. I was offered a commission as a Regular Army officer, Armor and helo pilot school. The commission was to be effective the date I would have originally graduated with back pay. No need to finish the last semester of ROTC. Obviously I passed and opted to go Navy.
Back to the Drill Sergeant question. My reserve unit was a training unit that taught Infantry basic and advanced. As soon as I made E-5, I was sent off to Drill Sergeant school. Then in the summers, I spent 3 months at Ft. Jackson every year instead of 2 weeks for my annual training. It was my summer job to bank money the next school year. I did 3 summers at Ft. Jackson as a Drill Sergeant. I also did a 5 month stint after college while waiting to go to AOCS. It was quite fun....
I enjoyed growing up around the Army and enjoyed my time in the Army reserve. I'm glad I went Navy for my officer career. This was greatly reinforced during my time in the joint world at U.S. Southern Command. Those Army dudes need to learn to relax and get a sense of humor.