How to study system design

Why it matters

System design interviews grade how you think, not what you remember. The interviewer wants to see you ask about scale, make a choice, say what it costs, and change your mind when a constraint appears. Reading more articles does not build that. Rehearsing it does. This lesson is the study plan the rest of the track assumes.

The idea

Treat every lesson as material for one sentence you can say in an interview, and every drill as a rehearsal of saying it.

A weekly rhythm that fits around a job

1. 1

   Pick one module

   Read its lessons across the week, in order. Ten to fifteen minutes a day is enough; two lessons a sitting is plenty.
2. 2

   Write the trade-off, not the summary

   After each lesson, add one line to a notebook in this form: "Use X when A, because B; the cost is C." If you cannot fill all three blanks, re-read the Trade-offs section.
3. 3

   Do the drill at the end of the week

   Out loud, with a timer. Thirty seconds of thinking, two minutes of talking per prompt. Then reveal the model answer and grade yourself.
4. 4

   Revisit what you marked Review later

   Three days after the drill, re-answer only those prompts. Spaced repetition is dull and it works.

Where the time goes in a real interview

A 45-minute design interview is not 45 minutes of drawing boxes. Knowing the shape tells you what to practise.

What to do with video and notes

Where a lesson has a video, watch it after reading, not instead. The text is the reference you will come back to; the video is a second explanation of the same diagram. Keep notes in your own words. Copying a lesson's takeaways into a notebook builds nothing; rewriting them as questions you could be asked does.

Trade-offs

Active study is slower per lesson and faster per outcome. If you have two weeks, do not try to finish the track; finish Foundations properly and drill it. A senior candidate with three weeks can filter the map to Must-know, Deep and work through those lessons and every drill.

In an interview

The habit that transfers most directly: always say the trade-off, unprompted. "I'd put a cache here. It cuts database reads by about 90 percent; the cost is that product pages can be up to a minute stale, which is fine for this use case." That sentence is the unit of a good interview. Every lesson here tries to give you one.