Efficient services help people to reach their goals more quickly, get repetitive tasks done rapidly on every turn.
1st example: When I track time I find myself repeatedly just typing in "31" (mins) instead of "30" because the 0 is too far away, I do not need to move my right hand for "31". All done with left, less excise is always feels good.
2nd example: The iOS app "Copy" allows to upload files to their cloud. To start uploading I click the "+" at the bottom, after I have selected (new) pictures from the gallery – which appear at the bottom of the screen – I have to click "Done" at the very top. Why is "Done" not at the bottom as well?