How many group exericse classes/week should an instructor limit themselves to avoid injuries?

I have never seen a standard, and I think it would be impossible to control because instructors can teach at multiple locations plus could even teach on their own in small groups outside.

I assume that this instructor is teaching all those classes at your facility and I am wondering why - from a business perspective - you would let this happen. Even if this instructor were to be the most popular one on the planet, you are exposing your business very much if this person all of a sudden could not or would no longer wish to teach for whatever reason.

Another thought: some instructors have a propensity to over-training bordering on a compulsion to exercising. If this is an employee, you may want to find a way to address it.

There are so many variables to consider. Are they all the same type of class. If she teaches different class formats, I don't see the dilemma. Even if she is teaching the same format, she is teaching. Proficient instructors now how to gauge themselves pretty well. If she is one that must workout the entire class, she is going to burn out.

Having been there and done that, it just is not good on the body.

I agree with all the comments thus far. Another consideration is keeping the classes and the instructor fresh. Knowing when to take some time off and refresh both mind and body is key. Avoiding extra load (i.e. subbing extra classes) and keeping variety for mental and physical variety is important. Burn out is a real and dangerous part of teaching and it needs to be addressed and recognized.
I've been a GF Director for many years and generally speaking many new GFIs teach 15 classes a week with ease. Over time, it seems many dial the class load back to 8 - 10 classes per week and supplement their income in other areas (i.e. training)

I teach 10-12 classes per week. The key for me is to not get a high-intensity workout in every class. Like others said, we are there first & foremost to coach and motivate.

A couple examples on how I handle different days:

Day 1, I teach yoga, cycling, and weights. I primarily demonstrate a pose, then walk around to cue form & alignment during yoga. In the cycling class, I ride the bike but mainly cue intensity changes--I do not push my own intensity as much. During the weights class, I lift moderate-heavy weights and make that my primary workout of the day.

Day 2, I teach dance, step, and water aerobics. I keep my dance movements low-impact and just quickly demonstrate/cue the high-impact options. I teach step with no risers (4" bench only), or even on a Mat-Step. I then make the water aerobics class my primary workout of the day.

It really depends on the person and what kind of classes they teach. My classes are very cardio intensive and require a lot of participation on my part. I can only do that so many times per week. But if I were able to add in classes that worked different parts of my body and gave my body a break, then that would be different. There is an instructor at my club who teaches at least 10 classes each week, but she has the ability and the classes vary.

My max for several years was 15/wk. Much depends on the type of classes and the instructor's physical involvement and age (lol). For some of us who have been teaching for decades, it is much more feasible to teach aqua, mind body, cycling and low impact varieties at higher frequencies than it would be to pack the schedule with high-impact options like we did in our twenties. I've seen peers of all ages who have suffered overuse injuries or professional burn out under the weight of an over-committed schedule. So, my philosophy is do what you love, give it your best AND do what it takes to take care of yourself for the long haul!

I myself have just finished a month and a half of 19 classes per week. It was very challenging....but do-able. I wouldnt want to live with that as my regular schedule...but it is possible to do it. I agree with all the other answers here...it really depends on the intensity of the workouts. It also depends on the variety. I wouldnt want to be in a class with an instructor who has taught and participated in say 15 cycle workouts....or 15 weight classes...but mixed up to different classes and intensities...that would be a different story. It really does depend on your instructor and the intensity they are able to handle...the real question would be...are the 10th to 15th classes still the same quality as the first 5 classes? If they are still quality classes...then the problem doesnt really exist. Your instructor has found a way to co-exist and teach without burning out. For this...you should be happy!! Your concern for your instructor is appreciated by her I am sure.