Last week a friend asked me for help with a rather simple LaTeX problem (he wanted to include an image and rotate it, which you can achieve with the angle option of the \includegraphics command). Of course, you'd find this solution also in the manual of the graphicx package, and I thus recommended to install the texlive documentation. Rather thoughtless, as it turned out. He later informed me that he didn't intend to waste more than 10% of the limited storage capacity of his netbook just for 'fucking manuals'. Hey, I understand! I wouldn't do that myself. :/
However, what I regularly do is to check the size of the package I'm planning to install. All package managers I know offer this possibility. Try for yourself. ;)
urpmq -y <name> urpmq -i <exact-name>
wajig search <name> wajig detail <exact-name>
pacman -Ss <name> pacman -Si <exact-name>
zypper search <name> zypper info <exact-name>
Most likely, the texlive documentation will turn out to be by far the largest package avaliable for your distribution. On Mandriva, for example, it is 500 MB in size. No, you probably won't want to install this package on a netbook equipped with a 4 GB SSD...