I’ve worked in a number of block scheduled schools and they are indeed far more effective than the traditional 50 or 60 minute daily allotment. The ones that work best rotate the classes over a 2 day period in a manner that also changes the time of day the class meets. (Every teacher knows the huge difference between a student at 8 am and one at 2:30.)
Still, short classes are only half the problem, which is what I’ve realized working with block schedules. You still have students working on 7 or 8 very different and very self-important subjects at the same time, stretched out over a long and fractured year.