I have to respectfully disagree with the poster who said anyone who has more than 25 things to do is nuts.
As David Allen has said all along the purpose of the project and next action list is to get all of those items that are clanging around in your head out on a list. Just because it's not on the list doesnt mean its not in your mind and keeping you from having a mind like water. My quess is that most of us have a lot more than 25 next actions. If the poster was refering to 25 things to do in one day it depends on the actions that are listed. Make 25 phone calls? Sure assuming they are quick. 25 minor but important things to do around the house on a clean up Saturday? Maybe. There are some things that require all day to do one thing.
My next action is list is very long. It details all the next actions on every single case. Not all are to be done today or even this week but that are there in front of me to evaluate. Like others on the weekly review I pull out the things that need to be done on a weekly basis and block out time. Those things show up on a daily to do list and I work better when I refer to that list as I go through the day. If I get through them and I have time because I have left time for other urgent matters than I go back to the to do list. Its a lot less overwhelming when its all in from of you and you have acknowledged what you have to do. Again, as David has said if the timing is impossible then its important to renegotiate the commintments or keep your to do list in front of you when you take on more work.