Sometimes it works well for one, sometimes not. What do you want? If you appear clueless and sign up for what you want, that usually can happen. I'm sorry you did not do the summer calc work; what math were you expecting to take this year? If you have the summer work available, I'd dust that off and start working hard on that (or drop out of the calculus class). If they literally stop you from signing up for Spanish IV, nothing you can do about that, unless you really want it and then you argue with them and tell them the guidance counselor told you to take it, etc.

If you are going to go to college, it gets even worse with what gets screwed up (since you have to make all the decisions) but there's always opportunities to make that work for you too. There are lots of "rules" with schools but so many students that often you can wriggle through the cracks and no one notices (if you are successful); I took courses for upper level students only when I was lower level, etc. Figure out what you want to do and make a plan for a couple years ahead so you have wriggle room :-) A lot of rules are based on what happens to "most" students. You can always decide to go for it and be the exception. Don't base what you do on what others say. Is there a pre-calc? Take that if you can instead of the calc this year. Don't go along with "their" program for you, they don't know you and what you want/need, they are just basing you on averages (and you ain't average :-)