Some people have voiced out their concerns because they feel that the 2 minutes that should be spent on brushing popularized by Sonicare is too short. It may be too short when you are the type of person who makes it a point to reach all portions of your teeth, but most people are too lazy to reach two minutes.
Some will not even bother to brush their teeth, and of course, this is not recommended unless the person would like to get some cavities and other dental issues. You may try timing yourself when you brush your teeth and see how long you usually take.