Is cramming ever effective?

For a test tomorrow, yes, within limits. For retaining anything beyond it, no. Cramming is a genuine trade rather than a pure mistake, and being clear about what you are trading helps you decide when it is defensible.

Massed practice does produce short-term recall. If the only objective is to pass an assessment in the morning and the material will never be needed again, cramming can work. Its weakness is that the material decays extremely quickly afterwards, often within days, because nothing consolidated it.

That matters more than it sounds in subjects that build on themselves. Mathematics, languages, medicine, law and anything cumulative punish cramming, because next term's material assumes this term's is retained. The debt compounds.

Even within a single night, some approaches are better. Retrieval practice beats re-reading regardless of timeframe, so testing yourself on past papers is more productive than reading notes again. Prioritising the highest-weighted topics beats attempting complete coverage. And stopping in time to sleep genuinely beats continuing, because sleep deprivation degrades recall, reasoning and exam performance measurably, so the last two hours often cost more than they add.

The wider point is that cramming is usually a symptom rather than a strategy. It happens because revision started too late, and the fix belongs weeks earlier.

If you are already in the position, cram deliberately: choose what to sacrifice rather than attempting everything badly, practise retrieval rather than review, and sleep. Then, afterwards, be honest about whether you needed the material to persist.

A final consideration applies to exams testing application rather than recall. Problem-solving subjects require practice at the skill itself, and no amount of overnight reading substitutes for having worked through problems, because the exam asks you to do something rather than to recognise something.