I am not an expert, but for lossless compression I believe the idea is that if there's a mismatch between the size of an encoded symbol and it's information con

I am not an expert, but for lossless compression I believe the idea is that if there's a mismatch between the size of an encoded symbol and it's information content (novelty) -- then you've got some room for lossless compression. Is that the case with URLs? Probably not directly. Certain atoms (.com, www) might be encodable to save space, but it'll not necessarily be a big gain.