I see "forgo" used quite a bit, and "forgone" is quite common too. I can't say I've ever seen or heard of "forwent" and in fact, I had to look it up to make sure it even was a word at all. Is it used much? Is there an alternative that is more common?
I suspect it's more common to say, for example, "I decided to forgo treatment" rather than "I forwent treatment." But why?