Repetition, like so many other things in life, is neither intrinsically good nor bad. It all depends on the situation, and your personal perspective.
For example, repetition in karate. Although sometimes it might seem tedious repeating the same movements, over and over and over again, there is a point to this type of repetition. Repeatedly doing the same kata helps you learn the movements so that they are natural, helping you to move on to the point where you can start thinking more in terms of application and proper technique, timing, etc. The more you do your kata, the better it gets, if you are putting any effort whatsoever into the process. Bring a thinking mind to it, and the progress will be obvious. Repeatedly doing kihon (basics) helps build muscle strength, flexibility, body control, and the end result is that the movements become a natural reaction to certain stimuli, performed correctly when needed. Boring to practice? Sure, sometimes it seems that way. But there is a definite point to it, which helps even the least philosophical person see a purpose (in these cases it also helps to think of it as "doing karate", which you enjoy, rather than "practicing", which most people think of as a chore).
Other kinds of repetition appeal only to sadists. Okay, maybe that's a little extreme, but things like a faucet that drips all night, the 14th time in one day that you hear the latest hit song on the radio, being able to predict what your mother will say before the words leave her mouth ("that's not music, it's just noise!") -- these things are annoying.
Another thing I find annoying is beating a dead horse, or in other words, endlessly rehashing and arguing the same points, when there is nothing new to be gained. I also dislike people using this blog's comments as a personal soapbox to attack someone else. That is why I made the decision a few months ago to close certain threads. See my post on September 29, 2006, if you want the details. I stand by that decision; in fact, time has shown that it was quite wise. I still get plenty of comments attempting to publish to these closed threads, and believe me when I tell you they bring nothing new to the table, and most of them are pretty belligerent (and many have been submitted multiple times, in the apparent belief that if they just spam me, then I will give up and publish them). So yes, I continue to censor my personal blog. I could defend myself by pointing out that I've blocked ALL comments, including those that I agree with. However, that's really not the point. The point here is not to "win" an argument or get your shot at someone, the point is that the time comes to close a discussion and move on. Period.