I do something similar to the author, though it does not follow his way of it. I basically keep a running check on things, almost daily. Everything that I see and hear, and sometimes feel (as in earth tremors), that could affect me, and affect the way I use my preps, and affect the choices I make in what I prep, goes through my mental prepping filter in the back of my head.
The conclusions are not always immediate, and sometimes go through a few mental revisions before I take action, but once I am satisfied I have come up with a workable idea and plan, if needed, I implement them. Sometimes I adjust things, other times I reduce some things, I often add items, and occasionally modify plans and procedures.
When there is a major world event; new scientific finding, historical revelation, or any discovery that can affect prepping needs and abilities; major change in my life; any significant local occurrence; I do a bit more thorough evaluation. Still more or less in the back of my head, but perhaps with a bit more concentration to speed the process, just in case there is something important. But it still is not a sit-down-and-lets-get-this-done kind of thing.
Now, I do perform an inventory and overall evaluation every 6 to 18 months, depending on just how much I have used my preps, what I have added to my preps, and on what I have seen on the news and gathered from the internet and my friends and family.
This is similar to what the author was saying. but since I have been keeping track on a regular basis, it usually does not take me too long. I do the physical inventory, and then do sit down (though not necessarily right then because I need some water, rest, and it is invariably time for my evening meds and their included pain medication) review against earlier numbers, my recollection and documentation on what I used and what I have purchased since the last inventory.
Once I am sure of my numbers, out comes the plan book or the computer fires up, and I review any changes I have made in my plans just to confirm they are adequate and correct for the situation they were devised for, after time for things to have run through my mind enough to fine tune everything.
Then I go over the rest of the plans, in light of where I am now, what I am now, what the world is now, what preps I have on hand, what preps I obviously need, what is available in the marketplace, what I can make, how much 'money' I have at the moment, and how much money I may have in the near, foreseeable future.
I let that all stew in my head a day or two or three, referring back to double check things as variables run through my head. At some point I find myself doing a quick, positive head nod, and I know it is time to make any of the changes that my mental processing has come up with as necessary, as good to have, as low priority, as long term implementation, and if-I-win-the-lottery.
And since WolfBrother prompted me for a list, even knowing how much I hate doing them, here is a list of things I pay particular attention to during these various observations on my prepping status for immediate, short term, mid term, long term, and permanent situations.
(Most of you, I am sure, are well aware of these, but I will list them anyway, because, since you also already know, I actually love to make lists and WolfBrother really did not prompt me.)
Edit to add: Actually, the list will come a bit later. Had something come up. But it will be here soon.
Just my opinion.