I’m leaving the country and I had this huge pile of change to get rid of, so I asked the bank and they said: “If you count it yourself and put it in little bags we accept it.”

Efficiency: I started counting this huge pile of change with a fairly efficient method: I went through it and put every coin in a separate pile, which I would count later.

This was hugely frustrating.

Enjoyment: Then I found myself picking out certain types of coins, and counting them and putting them in the bags at the same time. This strategy takes more time because you have to shift through all the coins like four times. However, for some reason it was a lot more satisfying.

This was almost enjoyable.

Point being: task completion time and measures like that are not the only measurements that matter. Sometimes a slower interface is better if it provides more motivation (feedback, enjoyment), which counts for a lot. If I’m not motivated, I’ll chat to my co-workers, kill time on the web, and so on, and in the end it will take me longer and there will be more errors.