The two minute rule is relative. David Allen came up with two minutes based on his observations as what he saw worked for most people. If taking time to do tasks in five or ten minutes is more effective for you than processing some of those items and you also have the stretches of time to operate in this way, then more power to you. However some things end up being projects with multiple steps and should be processed as such. Meaning they should be out of your inbox. Otherwise youll trip over those items and waste energy looking for whats new in your inbox.