It’s become fashionable, in recent years, to build a personal knowledge management (or PKM) system. The most famous PKM method is Tiago Forte’s “building a second brain”, which—odds are—you’ll have heard of.

Personal knowledge management promises to help you capture, organize, and engage with all the information that comes at you in such a way that you can resurface it exactly when you need it.

Great promise.

Flawed premise.

Yes, the architect who reads a paper about a promising new construction technique might want to save that paper so she can access it later, when she’s working on a a project where it might be useful—or, let’s be honest, fun—to employ it.

And yes, the software developer who reads an article about a new framework that could, one day, save him time might want to save that article and store any insights where he can find them later.

So too the lawyer who reads an ingenious defense might write up a summary for herself to refer back to decades later when—perhaps?—she might find herself arguing a similar case before a court.

These are some of the the loftiest examples of what we could use a PKM system for. And it might seem that—all other things equal—it’s a no-brainer for a knowledge worker to build a system like this. Surely it would lead to more creativity and better work?

The problem is that all other things are not equal.

For starters, how much spare time do you have in any given day? My guess is that you don’t have a free hour lying around every day just to read—with your full attention—the materials you come across that might be interesting someday, to analyze them, to summarize them, and otherwise process them into your personal knowledge management system.

Because simply capturing what is interesting isn’t enough. If you only ever capture, capture, capture, you’ll end up with a huge database of useless information. The promise of PKM even only theoretically becomes true when you engage with the material. But is it really worth spending your very limited time and attention engaging with material that’s not relevant right now?

This is the big flaw in PKM systems—the flaw people don’t like to talk about. Unless you put a lot of energy into capturing, organizing, and engaging with the materials you come across, immediately when you come across them, there is no added value. In fact, there are only costs, because any system requires at least some maintenance.

If you’re honest with yourself, are you likely to make the time to engage with information you come across that, while interesting, is not relevant right now?

It gets worse, too, because if you’re like me (and like most people), much of what you’re tempted to save isn’t nearly as useful as a new architecture technique, a promising software framework, or a genius legal defense. It’s probably more akin to long New Yorker articles, posts by influencers on social media who put a paragraph break after each sentence to appear relatable, and analyses of industry trends that you feel you really should stay on top of, but for which you have trouble articulating how knowing about them would materially improve your life.

There is simply too much information out there. Trying to capture anything that might be remotely interesting or useful is a game you can’t win.

There’s a reason our minds are very good at remembering what’s relevant right now and not very good at remembering what’s not. We’d be chronically overwhelmed if it were different.

If you’re currently in a happy relationship, you could read Jay Shetty’s bestseller 8 Rules of Love, to prepare yourself just in case something goes “wrong” with your relationship at some point. But why would you? There’s a million other, better ways to spend your time. Read that book when you’re in a period in your life when you’re reflecting on your romantic relationships. Do that and you won’t need a “second brain” to remember what you learned from that book—the insights will be clear as day and will stick with you as lived experience.

(Seriously, what do you remember from books you read years ago that weren’t relevant to your life at the time? For me, the answer is little to nothing.)

I’m not suggesting that you should have no system at all for capturing and organizing notes, documents, and other types of information. You should have a system. But it should be a simple system and it should be optimized for capturing, organizing, and engaging with what’s relevant right now—not with what might be relevant “someday”.

(The same is true for managing your to-dos and projects, by the way; your task management system should also be optimized for helping you manage the tasks and projects that are relevant now or soon.)

By all means, store what information needs storing. But give yourself permission not to feel FOMO about the infinite supply of ideas and materials that come at you. You don’t have to engage with all of them. Other people aren’t doing that either. You won’t be worse off for letting them pass you by.

Instead, focus on what’s relevant right now. And trust your first brain to remember what’s important in the long term, to filter out what’s not, and to surface the truly helpful ideas when you can actually use them.