There is no single correct study interval. The three below are the ones that keep coming back in the research and in practice; the difference between them matters much less than taking the break at the end. Press any row to load those lengths.
Start with 25 minutes and a 5-minute break if you tend to get distracted, and move to 52 or 90 minutes if you can already hold attention without drifting. Press a row in the table above and the focus and break lengths are set for you.
Note the interruption on paper and handle it after the block, unless it genuinely cannot wait. If it cannot, pause the timer rather than resetting it — the round you have already done still counts, and resetting trains you to abandon blocks at the first distraction.
It counts completed rounds and shows the total focus time for the session, so you can see the streak grow without keeping a separate log. Nothing is uploaded anywhere; the count is in the page.
Yes — that is what the rounds are for. Give each block a single named topic, so the timer's name field reminds you what this block was meant to cover, and the tab title carries it while you work.