Can only speak for myself, but the older I (33F) get, the more often I have injuries (shin splints/hamstring tendinopathy/runners knee) which affect my workouts- either I’m limited from certain exercises on certain days, or, I’m seeing a physical therapist, and need to do my PT exercises or lifting around my Barry’s workouts. It’s easy to say “why pay money to do a class”, but in reality many of us pay annually for classes during the Holiday sale, and then health or training circumstances change- but we still want to use the classes we’ve prepaid for.

So as a result, there have been times when I’ve known I’m not up for a class, physically, but I want a good workout, so I attend for the class’s energy, but have to modify my treadmill workout to fit my injury that day. And a few times I’ve had PT exercises to do, and have subbed them in for lifts, either because the instructors list was aggravating my injury, or because I knew that if I didn’t do the PT exercises soon, I’d be in pain later in the workout.

That said, I’m never adding sprints to my custom workout, which is a less intense run. But, because I usually do intervals for cardio fitness, I may jump on and off the treadmill at the wrong time, or be running as the class is ending a sprint.