that does not mean there is no value
Interesting angle, Zed. Never thought of that.
Like you, I got very little grammar in "grammar school". All those parts of speech and tenses you mention are greek to me.
I did learn "Nominative, Genitive, Dative, Accusative, Vocative, Ablative" in Grade 9 Latin because we had to memorize these terms, but I never had the foggiest about how to use them.
"Latin Authors" and "Latin Grammar" were one subject in my day. If you memorized the correct english translation of all the latin text, you could get 100% on the "Latin Authors" part of the exam, which accounted for 60% of your total mark. If you stuck in the root words in the "Latin Grammar" part of the exam, without attempting to decline them, you could pick up at least another 10%. So it was possible to get 70% on the exam without knowing the first thing about Latin Grammar.
Of course, this knowledge of latin roots has come in handy in ways I never anticipated when we studied Latin as part of the required curriculum in Grade 9. So I appreciate what you're saying about collateral benefits.
