That's a good point made there buddy. Sparring hard, for the lengths of rounds you have pointed out must take it's toll. Theres a lot of evidence that says headgaurds and bigger gloves like they use in spars has no effect, at reducing the damage, consistent blows to the head causes. Theres a medical term for what we call punch drunk, i cant remember what it's called now off the top of my head (sounds punchy I know haha) but the force delivered is still absorbed whether u have headgaurds and heavier gloves or not. It's direct trauma, like cuts and swellings, fractures etc that headgaurds and heavier gloves are good for. They reduce the direct trauma but the head blows are still the same, and some even suggest that headgaurds, can be detrimental, as they can spread the force of the blow over a greater surface. And also theres more chance of landing. Some hard sparring is needed I agree, as you have to condition your body to the stress it's going to endure in a live fight. But I think that in the U.K, and as you say, also the U.S. The hard spars,is way too much. Anyone that ends up suffering from punch drunk later in life, I bet that most of it is caused through hard sparring.