Some guys think a long spanking is always a good spanking. That is wrong. You do not need to spank a bum for half an hour to make an impression on a naughty girl.
There are certain moments that she will keep in mind:
The anticipation before it all starts:
The awful moment when you know it will happen right now:
(picture from northernspanking.com)
The pain in her ass:
When the spanking is over and you feel very sorry for yourself and your burning behind: