the whole letting it patch 5 times has never worked for me so i just patch one up completly, then browse to the folder that holds the wow.exe and do a quick sort by modified date.

Select all the files, not folders that were modified on the current date, copy them and paste them into the other account folders.

Works for me everytime. It's not the only method but it is another way to get the same result. You will of course have to update addons and whatnot.