Something that I still unsure about regarding 28 hours limit Permission to Engage in other activity

As international Students Living in Japan
i had several questions on Student Visa regarding 28 hours limit to engage in other activity especially in part time jobs:

1. do you need to include your break time within the 28 hours time limit?? Or only just the labor hours, in my case i didn’t get paid during break hours, and in the pay slip i notice that only the labor hours being actually counted and paid , example worktime 15:00 – 21:00 , labor hours 5.5 hours and break time 0.5 hours.

2. Is it true that counted from seven days, counting from any day of the week, must be 28 hours or less? I found it in JPMirai site

Any answer or related official article will help since i did asked my language school i kept getting vague answer, while confirming with my friends in other language school (different prefecture) the 2nd question is true that it is being counted from any days, but I some said it’s not, which make me unsure when setrig my schedule.