For example with Canon 5DM2 you get 60MB tiff files without compression. And with LZW-compression you get around 30MB.
Are you using 8 bit? LZW compression sucks on 16 bit images where the compression sometimes makes for bigger files than uncompressed. I do use Zip compression, which is better at compressing 16 bit, for any files I'll be moving around or sending to somebody. But no, I do not routinely compress my files...