The problem is that, once you know your opponent can chamberblock, it's rather easy to discourage him to do it. Just hold your attacks every once in a while, so that an attempted chamberblock will result in your opponent getting hit. After a while it becomes too risky for him to try.
That is why frequent chamberblocking is not a good idea. Your opponent can exploit your eagerness very easily. Using chamberblocks sporadically as a surprise move is, at least when used against me, a lot more effective.
There has been only one frequent chamberblocker I have had trouble with beating him and that was Bjordhinn/BJB. Not because he chamberblocked me, but because he attempted chamberblocks on my feint attacks, recognised I was feinting and let his attack go. For a long time, I just stopped feinting against him, but then I started holding attacks and he attempted chamberblocking a lot less. The risk was too great for the reward. It's a while since I last fought him, should look him up again
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