The only time I would suggest using clen is during a cutting phase. I would never use it in the off season, so I use it about once a year, maybe even a little less. During the off season, my goal is to gain new muscle. That requires a surplus of cals. Using clen is only going to eat into that surplus. If I find that I'm getting a little too fat, I can always dial the cals back a little. I can also add in a little more cardio. I usually do about 25min, 3x wk in the off season. In general though, you should only need clen when you are truely doing a cutting cycle.