A spaced repetition schedule is just a plan for when to revisit each topic: not how long to sit there, but which days you come back to it. The whole trick of spacing is to catch a topic right before your brain lets go of it, review it quickly, and then leave a bit longer before the next look. Get the intervals roughly right and the same topics that used to leak out of your head by Friday start sticking for weeks. If you want the "why does this work" side first, the what is spaced repetition post covers the forgetting curve. This one is purely about the schedule.
Why the gaps get bigger on purpose
Here's the one idea that makes the whole thing click: every time you successfully pull a fact back out of your head, it fades more slowly afterwards. So a topic you learned yesterday needs revisiting soon, but a topic you've already reviewed three or four times can be left for a week or two and still be there. That's why a good spaced repetition schedule uses expanding intervals: small gaps at first, then wider and wider ones. You're not being lazy by leaving longer gaps; you're spending your reviews where they actually count instead of wasting them on stuff you already know cold.
This isn't a study-influencer hack, either. When researchers compared the most common revision techniques, spreading practice out over time ("distributed practice") came out as one of the highest-rated strategies for remembering things long term, well ahead of re-reading and highlighting.
Source: Dunlosky et al., "Improving Students' Learning With Effective Learning Techniques," 2013.
The intervals that work: the 1-2-4-7 pattern
You don't need to be precise to the day. A simple, well-tested rhythm is to review a new topic like this: the day after you first learn it, then 2 days later, then 4 days, then 7 days, then roughly every couple of weeks after that. Some people call the similar version the 2357 method: learn today, review after 2 days, 3 days, 5 days, 7 days. The exact numbers matter less than the shape: short gaps early, longer gaps once it's sticking.
One thing that trips people up: a "review" is not re-reading your notes. It means covering the page and testing yourself: try to recall it from memory, then check. Spacing and active recall are a team; the schedule tells you when, recall is what you actually do when the day comes round. Re-reading feels easier because it is easier, and that's exactly why it works less well.
Building your own spaced repetition schedule in five minutes
Grab a calendar: paper, phone, wall, whatever. When you learn a new topic, write its name on tomorrow's square. When you review it tomorrow and get it mostly right, write it again two days ahead. Get it right again, jump four days ahead. Keep pushing each topic further along the calendar every time you nail it, and pull it back to "tomorrow" any time you blank on it. That's the entire system. A topic you find hard naturally comes round more often; a topic you've got stops eating your time.
A couple of rules that keep it sane: cap yourself at a handful of new topics a day so the future doesn't get overloaded, and keep each review short: five to fifteen minutes is plenty. This is little-and-often by design, not another way to end up doing three-hour sessions.
A worked example across a term
Say you learn the structure of an animal cell on a Monday. You test yourself on Tuesday (1 day) and it's shaky, so you keep the gap short and try again Thursday (2 days). This time it's solid, so you leave it until the following Monday (4 days), then the next Monday after that (7 days). By that fourth review it's taking you seconds, not minutes, because it's genuinely lodged in, not just familiar. Now stretch that across every topic in a subject and you arrive at the exam with a big pile of stuff that's already solid, instead of a to-do list you're trying to teach yourself from scratch in April. Same total time as cramming would have taken. A very different amount is still in your head when it counts.
What to do when you fall behind
You will fall behind. Everyone does: a busy week hits and suddenly twelve topics are "due." Don't panic and don't binge them all in one sitting; that just turns your schedule back into cramming. Instead, do the oldest and shakiest ones first, spread the rest over the next few days, and let the gaps reset. Missing a review doesn't undo your progress. It just means that topic slides a little further down the forgetting curve, so you pull it back to a shorter gap and carry on. The schedule is a guide, not a set of rules you can fail.
The low-effort version: cards and the Leitner box
If keeping a calendar sounds like admin, flashcards do a lot of the spacing for you. The classic upgrade is the Leitner box: cards you get right move into a pile you check less often, cards you get wrong go back to the daily pile. That's a spaced repetition schedule running on autopilot: the hard stuff comes round sooner, the easy stuff drifts to the back. Keep cards small: one idea, phrased as a question. "What are the two products of photosynthesis?" beats copying a whole paragraph.
Or let GCSE Boss run the schedule
The honest catch with any spaced repetition schedule is the admin. Working out which topic is due today, across ten or eleven subjects, is a real job, and it's usually the bit that quietly falls apart by week two. GCSE Boss does that timing for you: it spaces your topics across your actual exam-board specification and brings each one back round at the point you're likely to need reminding, so you revise what's due instead of whatever's nearest the top of the pile. You get the intervals without having to run the calendar yourself.
None of this is about doing more. A spaced repetition schedule is mostly about doing the same work in a smarter order: little and often, testing yourself, letting the gaps stretch as things stick. Pick one subject, try the 1-2-4-7 pattern for a fortnight, and check how much more is still there at the end. It's a calmer way to revise, and it's the one the evidence actually backs. You've got this.