Allen states that the main reason for writing down everything is so that you can achieve a "mind like water". The explanation is thus:
In karate, there is an image that's used to define the position of perfect readiness: "mind like water." Imagine throwing a pebble into a still pond. How does the water respond? The answer is, totally appropriately to the force and mass of the input; then it returns to calm. It doesn't overreact or underreact.When you write things down, according to Allen, it allows your mind to let go of all the mental tension required to keep track of all your ideas and tasks. Your mind can focus on doing one thing well, rather than be torn trying to keep track of everything that needs doing.
I am figuring out that writing down your tasks has another benefit that is making all the difference for me, which is to allow me to prioritize what I shall do.
Imagine a world in which you would visit a restaurant and order anything you want without a menu. It would be terribly inefficient because each restaurant is not prepared to make just any food. Restaurants typically focus on what is on the menu. This allows them to order the necessary food, use the correct equipment, and perfect a technique that will leave your food tasting delicious.
If the restaurant had to scramble to find ingredients, and the cook had to learn how to cook new dishes for every order, the result wold be lackluster. So, having a set list of items to order makes it easier for the restaurant to deliver consistent results, and makes the experience more pleasant for the guests.
Imagine, then that when you are sitting down on the weekend to plan your week. It is much easier to open up your menu of things to do, pick the best ones for the week, and then create the order for your work week.
Obviously, there will be more tasks than time to do them. This is fine. Presumably, you have selected the most urgent or necessary items for your calendar. Rather than forgetting or not having the time to do those leftover tasks, you have actively chosen to not do them yet. Having a comprehensive list of things to do is not about getting them all done; it is about giving you choices for which ones matter most at the present time. Choice is key.
What I am attempting to point out is that having a list of items to do, you are able to pick and choose what to do. It also helps you avoid putting less urgent items in your calendar that could have waited. Why would you do such a thing? Well, because when you sat down to plan, it simply popped into your head and seemed like it should be done. Whereas having a comprehensive list of those things that demand your attention allows you to weed out those things that can wait by allowing you to weigh them against the other choices.
How This Became Evident
Based on the David Allen quote, you might guess that I am a fan of his work, which is correct. I've used GTD with Moleskines and with Evernote. I've tried it with spreadsheets and other tools. Currently, I am using +Smartsheet, which I have used in the past. In this instance, I am using Smartsheet in earnest. I mean, I am REALLY dumping all my tasks on a sheet, something I did not do in previous instances.
One neat feature about Smartsheet is that I can connect it to my Google Calendar. So, those items that are due show up on my calendar. If I get the item done, I check it off as done. Otherwise, I can simply change the date for the next best time. I find this easier than managing tasks through the calendar.
There is also a task section for recurring tasks. Once I finish one of those, I change the date to the next instance. In this way, my calendar starts to fill itself out with tasks. I can look at what I already have schedules and am then able to select those things I think I can achieve in the gaps from among the list of tasks.
It is this available selection of tasks that made it evident for me that writing everything down makes it easier to keep myself productive. No need to mentally go through everything I could do. I can simply pick one of the many items already selected. There is always something to do, it is simply a matter of selecting an item.