I mean this seriously: why? High school math is not a rapidly changing field. Sure, you might have to slow down or speed up, depending on the class -- although, is even that true? Is the average student really changing all that much from year to year? -- but that means taking out the file for day 82 on day 87 or whatever. That's not a massive adjustment.
The material is unchanging. The students aren't going to be all that different from year to year. What's going on that it seems like common sense to so many people that teaching high school math requires a bunch of novel planning?