The stopwatch consistently proves it takes less time than using the keyboard. Apple's HCI research showed that people "lose" the time it takes to hunt and acquire the keyboard shortcuts.
assuming you're referring to https://www.asktog.com/TOI/toi06KeyboardVMouse1.html, I find this dubious for a number of reasons and would like to see Tog's methods and data. for example if I want to cycle through undo, I can hold down command and hit Z and shift-Z as many times as I want, as quickly as my fingers can press the keys. acquiring the menu item for this over and over would get tiresome quickly. similarly with opening new tabs and switching between them. I suspect his data only holds for inexperienced users using typical shortcuts in typical applications, not for expert typists who spend all day with their hands on the keyboard. the amount of complicated text manipulation I can do at speed with keys in emacs and vim would be absolutely infeasible if I were clicking through some massive menu.
I always found that study unconvincing. I am sure there are people who need to look at the keyboard but surely anyone who leaves their hands on the keyboard all the time and never looks down finds the keys instinctively.
