Alright so that is a little cheeky – yet it was the answer that is given for every question asked during the Information Architecture lecture at Nielson Norman Group's Usability Week. The worst part – it is true. You could see the decision makers (managers, strategy people, etc.) rolling their eyes in discontent.
There are no limits to the number of menu items you can have, or columns on a page, or anything else that you are trying to get a number from. Every case is unique, and to think there is even such a “rule” is asinine. There were a lot of people today asking those types of questions so they could run to their boss or designer to show off their new found glory of information. Actually, at first I could not believe people were even asking those types of questions – but then again:
“No one in this world, so far as I know has ever lost money by underestimating the intelligence of the great masses of the plain people.”
– Henry Louis Mencken