I only got to experience it for one year (and then we moved). But I liked it. We had “Lab days” on W/Th (Where W had periods 1, 3 and 5, and Th had periods 2, 4 and 6).
I was (and still am) the kind of kid who enjoys learning and school, so I really hated normal days because half of the class time was spent waiting for kids to get into their seats, waiting for them to shut up, waiting for them to get their notebooks out, waiting for the teacher to pass back old tests/homework. I always felt like so little time was actually spent on the lessons.
With lab days, we had twice the amount of time, so all that transitional time was a smaller portion of the whole.
In science classes especially, it gave us more opportunities to do better experiments.
It was a better learning experience all around. In college, I have continued this habit. I’ve done my best to pick classes that meet twice per week, with long meeting times, as opposed to picking classes that meet 3+ times per week, for only an hour at a time.
The only class that I have picked, in three years, which meets more than 2 times per week is the Statistics class I’m taking now.