We had five one hour periods a day for 25 a week. You did each subject 4 days a week for five subjects. In the first two years the extra five periods were 2 PE, 1 art, 1 music and 1 economics. By the time exams kicked in you could do a sixth subject and the spare was used for a hobby class or in some schools health/parenting etc. The main problem was if you were a STEM person in your last year you ended up taking calculus, statistics, biology, physics and chemistry. This left one subject which most people took English in. So a lot of people never did history (not available until year 11 (10th grade), or geography (same), classics etc and most had to drop a their language (if they took one as our choice was French or home economics/ metal work) after a couple of years because it didn't fit in. Summer school etc isn't a thing here.
I imagine it has changed but probably more options rather than moving to 8 periods as the day is mostly only 6.5 hours long including lunch although I do know some schools have some zero period subjects from time to time but the buses don't work for that and we have essentially no public transport. In my father's day they did 7 45min periods though.
