One thing we learned is that Montessori isn't for every child. My oldest did OK but he much prefers traditional schools and is thriving at his middle school (a public magnet). My youngest, on the other hand, loves the self-guided learning and pace. He's more organized and self-motivates better than my oldest which makes a big difference. He reads like crazy and finishes books in a week that would take me a month at least, not sure where that came from but he gets a lot of free time at school when his "works" are finished. Both kids are diagnosed with ADHD and so am I (my poor wife heh).
Another thing, the Montessori we attend is public so it still has to meet district and state testing requirements. That put it in an awkward spot where it could never be pure Montessori because of the district and state mandated testing. It also puts the teachers in an awkward spot because they're rated on testing results which contradicts the Montessori method. My wife got fed up and left last year and no teaches at a traditional public high school.
I live in DFW and the Montessori i'm referring to Mata Elementary. DISD is a notorious hellhole of a district but Mata is hanging in there. It's not perfect by any stretch but they're hanging in there and doing their best with what they have. https://www.dallasisd.org/mata