Same deal with DRY, the principle is obviously correct but people can take it too literally. It's so easy to get yourself in a huge mess trying to extract out two or three bits of code that look pretty similar but aren't really used in the same context.
The problem with DRY and generic rules around size, etc. really seems to be figuring out the boundaries, and that's tough to get right, even for experienced devs, plus very contextual. If you need to open up a dozen files to make a small change you're overwhelmed, but then if you need to wade through a big function or change code in 2 places you're just as frustrated.
