Some schools do teach Algebra II after Algebra I, but with some mixed success. Two points worth considering: The PSAT, given in 11th grade, covers geometry pretty extensively. So if you don’t know it by October junior year, you are at a disadvantage in the test. Similarly, many standardized tests (like Iowa tests) begin covering it then too. Those don’t really matter a whole lot, but it was a big consideration for us, who were hoping for scholarship money. Another point–IMO Algebra II is way, way harder than geometry. The material is just pretty tough. I’ve even taught it twice now and struggle with a few concepts. Heck, I think trigonometry is easier than parts of Algebra II. I think my kids benefitted from a little extra maturity before we got there.