The process relies on following the workflow. I know that when I stick to it, then everything works well for me. When I don't, then things fall apart.
You should "capture" the next actions as soon as they reveal themselves to you. Make sure that your capture devices are hole-proof.
I have a couple - yellow legal pad, in tray, and voice recorder on my Palm. And of course voicemail and email.
When I get back from a meeting, the notes go into the in tray. They do NOT go straight into a folder about the particular project/subject. I clear my voice recorder onto a page from my legal pad at least once a day, then add that page to the intray. Same goes with voicemail.
Email of course is its own entity.
Then, usually once a day, at the end of the day, I clear the in tray, updating NA lists as I go, filing the notes once completed. I scan the notes, and make sure that all NA's are organised.
But, as DA says, if I can't get to it for a day or several, I can relax knowing that everything is in a trusted system.
Urgent or small NA's I sometimes "Capture-Process-Organise" as a single step straight into my Palm
The weekly review is a much bigger task, going through everything.
And I am at the stage where my weekly review is actually starting to happen regaularly - three weeks out of every four!
Good luck with your journey