If you want to add cubes I would cut your stips to 3 3/4" as trying to work out your cubes with different measurements is a real PITA "ask me how I know LOL" which will give you 3 strips for each repeat.
If you are not going to do cubes then you could get 4 strips at 3 1/4" or 3 at around 4 1/4" the choice is yours.