I've had two accounts on a PC each, for pretty much all of my wow time.
Last summer I got Keyclone and a 3rd account.
I liked the 3-boxing quite a bit, but a few days later decided on 2 more accounts.

If you have the systems (hardware) or a computer strong enough to run five accounts, 5-boxing is amazing compared to boxing fewer.
In the end, its all fun anyway.