Not necessarily. At many YMCAs (in the US at least), unlimited group exercise classes are included with a monthly membership. 3 days/week, I teach an early-morning cycling class at a Y in St. Louis, using a "canned" format named SPRINT:
Understandable. I've found that I neither have the drive nor time (busy software developer) to create my own playlists and workout plans. I greatly respect instructors who do that week in and week out!
I find what LM puts together to generally be pretty good. I also teach their BODYPUMP and CXWORX formats (used to teach GRIT as well). By experience, I've learned that to keep class participants happy, it's best to rotate material every 2–3 weeks. That keeps me and them from getting too bored of a workout, but also allows them time to master technique and discover areas in which they can push a little harder. LM publishes new stuff every 3 months, and I've built up substantial catalogs of quarterly releases, so it works out pretty well.
I am also a software developer. When I first started teaching was back in the days of Napster before iTunes. When the iTunes music store came along it was like manna from heaven. For cycling, boot camp, and the occasional water aerobics classes it was easy to put together a playlist just choose songs based on the drills.
For classes where I had to stay on beat like step, cardio kickboxing (early on, it was a fad), and general strength training, it was a combination of buying 32 count aerobic mixes and creating my own consistent beat mixes music with CoolEdit (now Adobe Audition).
I could find plenty of 32 count combos by going to other instructors classes and turnstep.com.
My wife just started teaching for a local les mills type organization that has prechoreagraphed workouts and she loves it and her classes do look fun especially for people who naturally have rythym and can dance.
I had neither, but I could do pretty well to standard 128-136 bpm, 32 count phrased music.
LM formats, at least the ones I teach, mostly consist "counts of 8". With respect to beats in the music, each count is 2 beats. In BODYUMP, for example, a "slow" clean-and-press is 8 counts (instructor can comfortably and naturally say aloud 1-2-3-4-..., from start to finish of the movement), but it's indicated on the choreography sheet as 2x8. In SPRINT (HIIT cycling), I might say something like: "next interval is 25 seconds seated sprint, then 10 seconds standing power, then another 25 seconds seated sprint, then rest for 25 seconds". That equates to head-counting with the music of 8x8, 4x8, 8x8, 8x8; but strictly by beats would be 16x8, 8x8, 16x8, 16x8.
I can't say this phrase without cracking a laugh. Really.
$40 is an ok gym membership. All the treadmills and bikes you can ride.