The ability to add exercise variants would be crucial for clients, e.g.:

If I create a program where I program the pin press, the rack pull, or a squat with a multi-power rack, but my client doesn't have access to the necessary equipment, there should be a tab for each exercise with an icon indicating a change or variant.

In this tab, I will add "variant" exercises that my client can do if they don't have access to the equipment for the main exercise, or if my client has an injury, or even if the gym equipment is busy, my client can choose a "variant" that I have previously added.

Allowing me to add 3 variants per exercise should be sufficient, thus conserving resources in the application.