Most GTDers will tell you that you should have one inbox and no more. I do agree that you should have only one inbox, but I would argue that the concept of an inbox is a two-step process. The first step, or the “reception desk” of your inbox is in your head. Before you fire up Omnifocus and tap the quick entry shortcut, you need to make that decision in your head of whether or not you need to be capturing the task into your trusted source. The first rule of GTD is: if you can do it in two minutes, now, then do it.
Let’s say you’re walking to work and you realize you forgot something. First, you have to decide, is this something I can act on now and finish in the next two minutes? No, of course not. You’re on your way to work, and the thing you need is at home. You pull out your phone and open up Omnifocus to enter in a task. You could enter in a project, a context, a start time and flag the task so that it only pops up after you’ve gotten home and you can act on it. I’d argue that it would be better to enter the name of the task and then just close Omnifocus. Quick capture is about getting the thing in your head out of your head and into the inbox. It’s not about processing the task. I have this problem where I want to process everything right away. I’ve realized that I’m better off just dumping things into the inbox and leaving them to be processed during a daily review. The term “daily review” might not be the best one though, because reviewing Omnifocus just once a day might not be enough. I probably need to do 2-3 reviews a day. One in the morning, one in the afternoon and one at night before going to bed. Quick capture should be about peace of mind, not productivity, per se.