See also: "really" and "actually". An easy way to improve your writing is to do a quick edit and remove all instances of these no-op words then go back and adjust.
Indeed. Even if you're using a "better" word than "really" or "very" or what-have-you excess repetition of any word will dull the quality of the writing so it's a good thing to watch out for.
And it may seem that this is a mistake that is difficult to make but because of the difference between writing and reading, where one may spend many minutes or even hours writing something that only takes a few seconds to read, it's easy to forget that you've repeated a word too often.