I took three years of Spanish and got an A every semester. Even when it was still fresh in my mind, I was nowhere near able to hold even a very simple conversation. And now just a few years later it's all totally gone from my brain.
My mother's native language is Spanish and she never taught me, which I resent her for. But I still find it incredible how shitty my public school education in Spanish was. We really should be teaching kids a second language from kindergarten up.
I had 4 or so years of Spanish throughout various levels of school and never felt I learned much at all. I jammed Duolingo for a month or two before going to Mexico and was really surprised by how much I still remembered. I was able to test out of a lot by having a solid foundation that somehow had stuck with me, I felt pretty cocky going into my trip.
Unsurprisingly, my lack of practice speaking and listening made real time conversations nearly impossible even though I could still read and write well enough. That really didn’t help much with day to day stuff, you can always pull out your phone to translate what a sign says but there’s no substitute for being able to immediately understand and respond to someone. Several others have mentioned it but an academic setting is not a very good way to learn a language, the best is just continuous exposure to how it’s actually used. I taught myself Korean primarily from watching a lot of Korean shows with some supplemental grammar and vocab lessons, it was SO much more effective. I was conversational from the start and was able to connect on a lot of cultural references, after 6 months there I was pretty damn fluent (and even won the grand prize for a speech I gave entirely in Korean).