There are many paths that people take towards mathematical understanding, many paths have loops where material is covered over and over again at different level

There are many paths that people take towards mathematical understanding, many paths have loops where material is covered over and over again at different levels of sophistication. I feel that typical pre-college curriculums cover topics superficially-- just enough for the exams. Many students would benefit so much more if they held-off on calculus until they became fluent in "the basics". Instead you get students practically forced to take calculus in high school whether they're ready or not and then they need to repeat the material in college-- sometimes STILL under-prepared. For college-bound, it would be much better to slow down, focus on rigor and mastery of algebra, geometry, practical applications, and proofs. Then in college start with something much deeper and more comprehensive than your typical "Calc 101"-- maybe at the level of Spivak's Calculus text or Rudin's.