The MRU system probably works better than many users give it credit for. It adapts to the user's usage pattern without requiring fiddling with settings. But it can be annoying when a command used every day gets bumped because one happens to be using many different commands for an irregular task. So maybe a hybrid approach would be helpful...
3) provide a toggle (i.e., a checkmark) for pinning any MRU item—so it "sticks" at the bottom of the list rather than getting bumped from the menu.
This would provide a natural and easy way to keep an often-used command on the menu, and an equally easy way to remove it when the usage pattern changes and/or there's no longer room for it. Even if the current system generally works fine, this would provide the means to easily lock some commands temporarily while doing the sort of irregular task that would otherwise cause all existing commands to be bumped from the menu. The current maximum number of commands could be increased from 8 to, say, 12, to allow room for some pinned items without restricting the number of unpinned commands.
