First and foremost, the Inbox should be emptied whenever you can process it, although its recommended to do it every 24 to 48 hours. David Allen addresses this in Making It All Work:
Use and Empty Your In-baskets
This practice should be self-evident by now (if it wasn't to begin with)--you've got to use your in-baskets for them to create control and relief. That doesn't mean just putting things in them--you've also got to get them all out again. One of the best standards to reinforce until it becomes automatic is getting all your collection buckets empty--e-mail and paper as well as your voice mail and answering machines. A great target is to reach to zero with all your input every twenty-four to forty-eight hours. Bigger pileups will always happen, but those should be the exception, not the rule. (Making It All Work
I think both of your other questions are addressed in the following guidelines set forth by David Allen in Getting Things Done:
- Process the top item first
- Process one item at a time
- Never put anything back into "in"
(Getting Things Done 122)
David Allen goes into further depth about why you should process your in-basket using this method, but the primary reason behind it is to give equal credence to each item to be processed. He goes on to explain that (1) "Emergency Scanning Is Not Processing" and (2) it doesn't actually matter if you process using a first-in-first-out method or a last-in-first-out method so long as you process one item at a time.
Regarding the length of Someday/Maybe lists, it's important to realize that you can have multiple Someday/Maybe lists, which David Allen identifies as "Special Categories of 'Someday/Maybe'":
More than likely you have some special interests that involve lots of possible things to do. It can be fun to collect these on lists. For instance:
- Food--recipes, menus, restaurants, wines
- Children--things to do with them
- Books to read
- CDs to buy
These kinds of lists can be a cross between reference and "Someday/Maybe"--reference because you can just collect and add to lists of good wines or restaurants or books, to consult as you like; "Someday/Maybe" because you might want to review the listed items on a regular basis to remind yourself to try one or more of them at some point.
(Gettings Things Done 169)
Now then, if you do find it overwhelming to look at this list (and I admit I feel some overwhelm when I look at mine), make sure that you also are reviewing it on a periodic basis and deleting items which are no longer relevant.
Breaking it Down Through Batching
OK, so as to the actual matter of how to avoid becoming overwhelmed by your Inbox list my response is particularly more subjective. My recommendation is this: break it down into batches so you can do it as you can, when you can. I prefer to use small pieces of paper, one for each item. I take a bunch at a time from my physical inbox and process it into the necessary projects and actions in my electronic system. If you want to use a list on a full sheet of paper, I recommend you tear off the list at a certain point (such as half a page) and process that small portion. This makes the processing more manageable because you are looking at less stuff at one time and you get more momentum doing it because the list is smaller. I think this is what you mean by "split up the inbox in multiple lists." And I would recommend it, personally.
Allen, David. Getting Things Done: The Art of Stress-Free Productivity. New York: Penguin Books, 2001. Print.
Allen, David. Making It All Work: Winning at the Game of Work and the Business of Life. New York: Viking, 2008. Print.