4 x 45 study session
The 4 x 45 study session is 4 blocks of 45 minutes with 15-minute breaks between, then it stops. That is 3 hours of work and 45 minutes of rest, 3 hours and 45 minutes from start to finish. There is no fifth round waiting, and no decision to make at the end, because the decision was made when you started.
That is what separates it from the 45/15 page, which uses the same numbers but repeats until you stop. A fixed session is useful when you struggle to quit as much as you struggle to start: the plan is already made, and the finish line is visible from the first minute. 4 blocks is also a common shape for a study day. Two subjects in the morning, two after lunch, or one subject worked through four stages.
This session suits students with a revision day to fill, and anyone who wants to commit to a whole morning up front. Do not use it when you have less than 4 hours free, because you will not finish and a half-run session does not feel like the plan working. For a shorter commitment, 45/15 lets you stop after 2 rounds.
Questions
how long is a 4 x 45 study session
3 hours and 45 minutes: 4 blocks of 45 minutes and 3 breaks of 15. The session ends after the fourth block, so there is no final break to sit through. Start at 9 and you are done before 1.
is 4 x 45 the same as 45 15
Same block and same break, different ending. 4 x 45 runs exactly 4 rounds and stops. 45/15 keeps going, with a 30-minute break after every fourth round, until you close it. Pick the fixed session when you want the end decided in advance.
what should you do in the 15 minute breaks
Leave the desk. Eat something in the first break, walk in the second, and use the third for whatever you have been putting off, like a phone call. Keep each to 15 so the fourth block starts while you still have something left.