The only language I’ve studied beyond English is Spanish. Yes, conjugations and formal/informal forms are difficult to learn and memorize. I spent many years in classrooms studying Spanish, but never put it to any practical use. I’ve lost most of what I’d learned.
When my niece taught abroad, she worked mostly with children — business people sometimes. The children she taught would attend regular school all day and come to a different school at night to learn English.
In the States, traditionally foreign languages are not even introduced until middle school — age twelve to fourteen. Most students complete the two or three years many colleges require for admission and then give it up. In fact, after three years, my son has given up German class. He cannot see a practical use for it and so he opted for business electives instead. Interesting how cultural differences direct our choices.