Sure, it can’t hurt. But if you can set aside 20 or 30 minutes a day at least twice a week for a more structured workout that would be more helpful. I view GTG as a sort of side training to help improve fringe skills, rather than a primary training approach. Although it is far better than nothing, and you will still see results. 15 sets is a lot that’s about once per hour if you sleep 8 hours. You might try doing 2 sets at a time but half as often. Seems to me it would be less cumbersome to just do a workout.
In any case I’d suggest some leg work too. Pistol or shrimp squats are a great go to.