Course offerings can be somewhat fluid, in the sense that some courses may be in the schedule but canceled without much warning, or courses such as 290 seminars may be announced later on in the game.  Shopping around is a good strategy (that is, register for more courses than you will actually take, go to the first meetings of all of them, and decide which you want to take, dropping the others - as long as you have 12 units!).

In addition, some courses are offered only every other year, and are sometimes canceled in the year they are supposedly offered.  It's wise to have an idea of several courses to take for all your requirements, (e.g. breadth, depth, methods, etc) just in case one you need isn't offered until after you've had to take your orals.

Also, check that you're satisfying your requirements with your Guiding Committee (the committee you establish in your first semester/year, including your Guiding Professor/PI and two other people who can advise you on orals preparation/coursework) and your Graduate Advisor or the Head Advisor.  Especially important to check your breadth requirement!