the instructor in my dojo is often absent and I'll have to take over the class. when I'm teaching I don't get to do many techniques because I have to run around the class correcting almost everybody (I'm perfectionist like my instructor).
I come to wonder when do instructors train?
First off David I would say that you could look at the teaching experience as an opportunity rather than a hassle. Remember it is also training, you are training in teaching.
Secondly you can review every time you do it and if you find you 'have to' run around correcting too much that could be an arrow pointing to something you need to learn, it's all part of studying.
If you want to do more for yourself (at the same time) then I'm sure you can find a way. You know, letting the students just get on with it without interference for say fifteen minutes or so is not a bad thing.