DVD-5 single layer, single side

DVD-10 single layer, double side

DVD-9 dual layer, single side

DVD-18 dual layer, double side

With the dual layer discs, the first layer had to be larger than the second layer. There was a slight pause when switching layers, and care was taken to place the layer break at a spot to hide that pause as much as possible. At least on the discs where the author took pride in work unlike the YT decisions on when/where to place ads. Although, I've seen some really poorly placed layer breaks too.

Fun fact, I remember my french version of Reservoir Dogs switching from first layer to the other exactly during the torture scene, with the pause you are describing. Absolutely no care taken. Or maybe to put this at the worst moment possible. What a turn down !