Studying against a visible countdown does two things at once: it makes starting easier (committing to "25 minutes on this chapter" is a much smaller ask than "study until you're done"), and it protects your session from silently running long or short.

• 5 minutes — a quick flashcard review or a warm-up before a longer session.
• 25 minutes — a single focused interval, the classic Pomodoro length. Good for reading a set number of pages or working through a problem set.
• 50 minutes — closer to a full class period, useful for deeper work once you've built up focus stamina.

Whichever length you pick, take a real break when the alarm goes off before starting the next session — the break is part of what makes the technique work, not a distraction from it.

Run the timer in fullscreen mode to remove everything from view except the countdown itself — no navigation, no other tabs' worth of visual noise on screen, just the time remaining.