You run. You hit the bag. You spar until you're empty. That builds heart — it doesn't build the specific physical qualities that decide close fights. Hard work is the entry fee, not the edge.
Random circuits and ego lifting aren't strength & conditioning. They're noise.
Done wrong, that noise leaves you slower, stiffer, and one bad shoulder away from a cancelled camp. You spend the effort — you just don't buy anything with it.
Two boxers of equal skill walk in. The one prepared properly hits harder, recovers faster between rounds, and is still dangerous when the other man is only surviving. That difference is engineered — and it's exactly what this programme builds.