I've heard a technical explanation for keeping IC's short and speaker cables long, but almost all the anecdotal evidence I have heard (and experienced myself) has been the other way. In my personal experience, I've never had to deal with either IC or speaker cable longer than 5m, and the tech explanation was dealing with cable lengths of greater than 26ft.
Currently, I run 2m ICs and 2.5m speaker cables. This configuration was significantly better than 1m ICs and 5m speaker cables that I had been running before...