I'm in the process of finishing my basement.

I noticed that there appears to be two ways to attach wires to the receptacles. the screws on the sides, and little holes on the back, that you shove the wires into.

The little holes sure make things faster. After doing 3 plugs using the little holes, I decided to look at the other plugs in the house. None of them use the little holes, all use the screws. What's the deal? Are we allowed to use the holes? Is it bad practise?

Cheers
Kevin in Ottawa