I don't think it's too far off that at the moment, actually. He's been in just about every book of late. Six of the last seven main books, I believe.

If any characters being done to death, it's Vimes. I'd fully expect him to be in "making money" as a side character as well.

And of course, let's not mention the Igors. Technically, different characters, but still.

More than overdone