Originally, ALL schools had eight 40-minute periods per day. A teacher's teaching load is still defined in terms of the number of 40-minute periods they are required to teach. It was only around the very late 80s that some schools experimented with 6 periods, and I don't recall four being used until at least the mid 90s. And eight was still the most common at the turn of the century. Everybody coped with eight, no-one thought there was an issue with 40 minute periods. Having said that, I prefer 6, but only because I am used to it now.My school had 8 period days but 5 on sport's day lol (where I suppose the typical last free were where sport arvo was).
So recess was at completely different times on sports day, a 20 min recess and then lunch whereas during the other 4 days, we had a 10 min recess, 40 min lunch and then 20 min recess.
It seems that most people just prefer the number of periods they are used to having themselves. It annoys me when someone says things like "all schools should have 5 periods a day" as if that is some number that can be proved to be optimum for all schools/students. They are dictators in the making, and probably have imagined a plethora of arbitrary rules/laws that should be imposed on the community.