Distractions? One day, I came to class a bit late to find that a voodoo ceremony was raging in the house next door. And since we have no air conditioning, the mat is only surrounded by big windows only protected by iron bars. As a result, it was like the event was going on in the same building. The drummer was good, and I confess that while I was changing in the ladies' room, I really felt like dancing. But when I reached the mat, I found everybody training happily, ignoring the racket, and I did the same.
Once we were on the mat, it was just us and O Sensei.
Also, my karate school was twice forced to find refugee in a fitness club - a different club each time, and each time, we had to put up with the music and the roars of laughter of the club members exchanging jokes as they lifted weights. That also was good for developing our concentration.
I really like the idea of outdoor training, too bad it's not easy to find a safe place to do that where I live.