hey. i know most of their timed intervals have the 45 seconds on 15 off pattern, but i always end up doing 45 on and 30-40 off , it is comfortable for me . thats fine right? with 15 seconds i find it difficult to change some weights and get into the exercise. i feel like as long as you keep your muscles warm and don't take too long of a break, it doesn't really matter . ?