In Australia, it's not just little side roads that run by school entrances that have this rule; the school zone thing applies even on fairly major free-flowing roads. Two examples I can think of are
As the usual speed limit is quite a bit higher at 70km/h, driving at 40km/h (25mph) outside these times would make you, at best, a rather annoying obstacle to surrounding traffic.
https://www.google.com/maps/@-37.9293496,145.0051951,3a,59y,...
https://www.google.com/maps/@-33.7710688,151.0985503,3a,75y,...
As the usual speed limit is quite a bit higher at 70km/h, driving at 40km/h (25mph) outside these times would make you, at best, a rather annoying obstacle to surrounding traffic.