As I make the rounds at summer institutes, I meet folks who teach physics on all sorts of schedules. It is a universal truth that everyone's schedule stinks, that it was designed by trained boardroom monkeys, etc.
Thing is, there's a constant, legitimate tension between those who want lots of shorter class meetings (math, foreign language) and those who want longer chunks of time, even if that means missing a contact day or days (English, Studio Art). And thus the problem for physics: we kind of fall into both categories. We need to see our students every day -- physics, like language and hard tack, must be digested in small, frequent chunks. But, we need that weekly extended lab period, because data collection should be a slow and careful process without time pressure.
Toward the end of the previous century, a good number of physics-clueless administrators were trying to sandwich a year-long AP physics course into a single semester. While it is true that a full year of 45-minute classes is the time equivalent of a half year of 90-minute classes, anyone with a pea for a brain and a few days of experience in a physics classroom can explain that time-equivalent and actually-learning-stuff-equivalent are not the same thing. The College Board even experimented with offering a January AP exam to those who were forced to take AP physics from September to January only, with disastrous results.*
* Try proposing that the football team condense their practices... instead of two hours a night, four nights a week in the fall, just take the two weeks at the end of the previous school year after AP exams. The team can practice all day, every day, to get ready for the season. Then in the fall, we cancel football practice so as to teach classes all the way to 6:00 PM. And the team will be ready to show up and win on Friday nights. Right?
When I first became a consultant for AP, my mentor warned me to budget a good half hour per workshop to discuss schedule complaints, especially block schedule complaints. I've tried to turn complaint time into a positive discussion, by collecting thoughts and ideas from participants about adjusting to whatever necessary schedule.
In my own mind, only two schedule approaches are truly untenable for AP Physics: (1) Single-semester AP Physics B as a first-year course, and (2) Any sort of sandwiching both Physics C Mechanics and Physics C E&M into a single, first-year course.
Everything else can be finagled. Generally, wherever possible, design an approach such that students see the same material multiple times throughout the year. Four weeks on a topic in September is much less effective than two weeks in September, with the other two weeks of practice scattered throughout the rest of the year.
* Teaching 45-60 minutes daily, but without an extended lab period? No problem. After the first experiment, take care of data collection in class, even over multiple class days. But do most of the analysis out of class as homework.
* Teaching 90 minutes per day on alternate days? That's fine. You'll have to do some tricks to maintain attention for 90 minutes, since not even physicists can sit still for 90 minutes of physics lecture. The point is, the students' brains will have the necessary time to process what they've learned, and to develop the "muscle memory" they need. This is one of the better block schedule approaches.
* What if you get AP Physics B for just the spring semester on a block schedule, but everyone had physics last year? That's not a problem. Be sure that the prerequisite physics course is rigorous, preferably at the AP level but just much slower than AP. (Here's a post discussing just such a course.) Then don't do explicit "review," but start the year with something new; review previous topics in context throughout the year. Just be sure that no one can get into the AP course without the prerequisite.
* Here's a common scenario: "Honors Physics" in the fall on a 90-minute daily block, then AP Physics B in the spring on a 90-minute daily block. I would approach this the same way as the previous situation. Teach the honors course at the AP level, but slowly. Don't just do the mechanics portion of AP -- actually branch out and cover many topics. Then the students who just take the first half of the course will be well served with a broad-based introductory course, and the AP students will have a wide foundation to build on. Again, be absolutely firm about requiring the prerequisite.
* What about teaching AP Physics C - mechanics as a first-year course? Many folks do this successfully, because Physics C - mechanics is really a semester-long course in college. My own approach would be to spend the first half of the year teaching at the algebra-based physics B level. Then, start the course over from the beginning in January, overlaying calculus approaches onto the previously-learned concepts.
I have no doubt that other teachers have more and better ideas. Post them below! But please, no kvetching. You're stuck with your schedule. Share your ideas of dealing successfully with difficult situations; ask how others would approach your own schedule. But there's no point in telling the world how awful your administration is.*
* Mainly because the world probably already knows. :-)