First of all, not all teachers who have taught in schools with a variety of schedules favor the four-block-day schedule. Math and foreign language teachers, in particular, find that it's better to see students more often for a shorter period of time than to see them less frequently for 90-95 minutes. While it's true that art teachers and science teachers who work with labs find the long class periods easier, many teachers believe that the long class periods sometimes result in wasted time. Group work and class discussions sometimes go on too long, students take longer than necessary with writing assignments, etc.
In addition, many students have a hard time with long classes. Some, like my daughter, dread Wednesday or Thursday because their least favorite class seems never-ending. The current schedule makes difficult or less interesting classes more tolerable. Also, many students find school boring as it is; longer periods won't help. This is especially true for less academically oriented students and those with short attention spans, who may do even worse with the new schedule. Since PAUSD is presumably trying to address its achieve-ment gap, I believe that this is a valid concern.
Although I like the idea of classes beginning a little later, I think late-start Thursdays first semester help. Maybe the school should consider keeping the late-start Thursday second semester, giving students a chance to catch up a little on their sleep.
Finally, if the proposed purpose is to cut down on students' stress level, I'm not sure that the new schedule will achieve this.
The only positive from the students' point of view that I can see is that for 4 days they only have to focus on homework for 3 or 4 classes instead of 5 or 6.
I hope that the current administration and faculty have given a lot of thought to this change. My daughter and I have often discussed the differences between Paly's current class schedule and the one where I teach, and both of us strongly agree that Paly's is superior for a variety of reasons.