I suspect so. My grammar school years(the 50s) were passed in a Calvert System private school for Americans in Istanbul. I was an average student. After I got home I was so far ahead of everyone else that when I hit Algebra in high school it almost got me because I had not had to study for my straight As for three years and the tools were rusty. I got more history and everything else in what was known in the States as "social Studies" than I got in the rest of my public school career. As I look back on the schools in Florida and Virginia that I attended to 1964 I know that they were much better than anything now.
My wife is a primary teacher here in NW Florida where the schools have always been 10 years behind those in the northern part of the country. That used to be a liability. Now it is a relative blessing.
There it is. My experience is similar. I started kindergarten in 1958 in the US Army school system, and continued until late 1966 when my parents divorced.
Like you, I found myself far ahead of my peers when I first attended the public schools. Their curriculum was so far behind the comparable grade levels in the military schools, that I coasted in neutral for a couple of years before having to seriously apply myself again.
I never did lose the lead I had on my public school peers. When I left high school, I was testing at a second year college level.