Full productivity on dumbphones was realized when you learned you could hit 1 to activate the first item in a menu, 2 for the second etc. 5-2-3 boom new text message
Not failing to mention how handy that 'Menu-523' came in handy when the dpad wore down(usually the first keys to fail on a feature-phone). It kept me from having to buy a new phone for months.
Not to mention writing a text while driving, all without taking your eyes off the road...