I had been training for about eights year before I graduated from college and got my first job. I was cruising malls, showing off the size of my baton to all the cute girls. But in that job I got my very first taste of use of force and "defensive tactics".
My knowledge of MA at that point had been offensive. I never considered the defensive aspects until I got into my first working "fight". It was a slug match, right at the front doors. In the end it didn't look good, me dragging some jerk through the mall, unconscious while blood was splattered all over my pristine white shirt.
The worst part of it, everything up to that point that I'd learn (next to the punching and kicking) hadn't worked. For about the first two years of my career, before I got on with the housing police, the scene was the same - heavy handed, but thankfully I never landed up in jail, or anyone other than management questioned me.
I then talked to my Sensei when when I joined the housing authority I had gotten in to a couple of scraps there and decided I'd burn out before I figured this would work.
I blamed my art, Goju Ryu, and before that Shotokan, for my failings when I shouldn't blamed myself. My sensei and I had a bit of a heart-to-heart and he showed me some of the stuff in Goju I could apply. When I took a "Defensive Tactics" course...what a load of crap. BUT...I learned to mix both together and become comfortable with my own style.
In answering you question, I didn't learn to unlock the foundation of my art and apply it to my job until well after. I don't have much love for defensive tactics courses, simply because I believe that many of the courses are watered down.
Use of force tactics should be a part of the life long learning of any LEO, not just those that decided to take a 2-day course and then forget about it and do what works for them on the job anyway.