A sad truth about productivity aspirations: Sometimes, maintaining a system that’s supposed to make your life easier can feel like the hardest part. Even the best-designed calendar app doesn’t actually work if you have to force yourself to use it; eventually, updating it becomes just another unchecked item on the to-do list.

Which is why I’m both intrigued by and a little wary of the bullet journal, a diary/calendar/to-do list/planner system that, over the past several months, has rocketed to popularity, become an Instagram star, and developed its own cult following. It’s been described as “a powerful productivity tool,” “better than any app,” “a modern Filofax,” and “KonMari for your racing thoughts”; the bullet-journal website is dotted with effusive testimonials from users about how it’s changed their lives.

And yet all of this feels kind of counterintuitive, once you understand how the bullet journal actually works. “The thing I’ve noticed is that the complexity of the system is inversely related to the number of people who will adopt it,” says behavioral neuroscientist Daniel Levitin, author of The Organized Mind and the forthcoming book A Field Guide to Lies. Put another way: The more complicated the system, the less likely it is that people will actually stick to it — “and the bullet system is complex.” The basic building blocks of a bullet journal are called “modules”: a “future log” of big-picture planning, a monthly log that functions as a calendar and shorter-term task list, and a daily log for more fine-grained scheduling, all held together by an index page and a system of symbols to indicate notes, reminders, and appointments. Here’s a video that breaks it down:

And users haven’t just embraced the complexity. Some have taken it upon themselves to add more layers, customizing their bullet journals with all kinds of extras: goal charts, weekly emotion logs, baby tracking, and even the weather forecast. Search for bullet-journal photos on social media and you’ll find yourself staring at a gorgeous wall of productivity porn.

So what’s the draw? In part, Levitin says, a bullet journal is appealing because it makes it easy to accomplish what he calls “externalizing your memory.”

“In other words, don’t just try to keep track of things in your head. Somehow get what’s in your head out there in the world, whether that means writing it down in a journal or on little three-by-five index cards, covering your desk and your fridge and your walls with Post-its, or making voice memos,” he says. “Some ways of doing that are more elaborate than others, but anything that gets it out of the head is a good thing.” There’s no one gold standard when it comes to organization, he explains, “but there are some general principles that an effective system would follow,” and externalizing is high on the list.

The reason: Your mind is precious real estate — most people can only pay attention to three or four things at a time — and transferring your to-dos frees up space for other, more immediate needs. “If you’re at work and you’ve got these voices in your head like, ‘Don’t forget to pick up the dry-cleaning,’ and ‘We need some milk,’ and ‘I have to pay this bill today,’ and ‘I have to call back Aunt Tilly,’ that’s four things … you’re already at your peak and you’re not even doing your work,” says Levitin.

Seems reasonable. But externalizing isn’t a unique feature of the bullet journal — it’s the point of pretty much any organizational system, including Post-it wallpaper. The bullet pulls ahead for some people, though, with its all-encompassing nature. It’s sort of a spin on environmental cuing, or the concept of placing reminders where you’ll encounter them organically (like placing an umbrella by the door before you go to bed, for example, if you know it’s going to rain the next day). Put your whole life — your work to-dos, your social calendar, your grocery list — in one place, and the odds are higher that you’ll open the notebook for one thing and end up seeing a reminder for something else.

In that way, some people may see the bullet journal as simpler and more helpful than keeping separate systems for separate purposes. And devotees insist that it really is simple, once you get the hang of it. But its relative complexity may actually be the key to its effectiveness: Unlike a numbered list on lined paper or an empty, premade calendar grid, the bullet journal forces you to do more than just write. It requires chart-drawing and symbol-making, and — as a quick Instagram search for #bulletjournal or #bujo will demonstrate — also leaves room for illustrations and color-coding and other forms of productive beautification. (Creator Ryder Carroll has declared that “you can use it as easily for a sketchbook as you can for a math book or a shopping list.”) It is, in other words, a cornucopia of motor and cognitive tasks, some more demanding than others, that collectively help to relieve your brain from the stress of doing any one thing for too long.

The key is in the diversity: Balancing deliberate activities with more mindless ones, Levitin explains, helps you to mentally refresh. “We should make time and space to alternate” between focus and “mind-wandering attentional mode,” he says. “The research tells us that if you can take time off from your workflow and let your mind wander — maybe doodle, listen to music, draw pictures, just stare out the window — those periods of inactivity are actually essential to having productive periods of activity.”

The flexibility of a blank notebook, Levitin adds, can also help get your juices flowing more than would tapping everything out on a screen. “When you’ve got a piece of paper in front of you, it sort of encourages you to expand your visual field and expand your imagination,” he says. You can build on ideas, or experiment with different ways of representing them on the page. Past research has suggested, for example, that you may retain information better if you write it by hand rather than type it out; one study published earlier this year took the idea a step further, finding that drawing the things you need to remember may be even more effective than writing them down.

It’s more time-consuming than an iCal, but that’s kind of the point: “You can reduce the amount of things you have to do by transferring things by hand,” Carroll has explained. “If a task isn’t worth the time to rewrite it, it’s probably not important. Spend time with things that are important and be mindful of how you spend your time.”

As Levitin stressed multiple times, the bullet journal won’t work for everyone; there is no organizational system on earth that will. Part of its appeal, though, may stem from the way it plays to the workings of the brain — a fact that makes the system seem a little less daunting (at least in one disorganized writer’s opinion). And, at the very least, it’s a great excuse to buy a new notebook.