using /focus instead of /assist is the currently recommended method ... but also introduces a level of complexity that can be avoided at the lower levels... allowing people to get use to multi-boxing.

i generally recommend moving to /focus between 15 and 20. by that time, most people have a handle on multi-boxing and understand what to expect... so throwing in the macro editing and the various /focus issues can be concentrated on better .. and debugging the process is easier (since they don't think it's the multi-boxing, just some macro thing)