I've done it on and off for years. I'm certainly no CF hater, but it got very hard on my body and I've backed off. For developing street fight fitness I think it's excellent. I miss it, but my shoulders won the argument. The very fittest I've ever been was last year about this time when my training for the SAC was just ending. That was 90 minute CF sessions 4 days a week and rucking 2 days. I was a tank until the shoulders gave up.