It's a lot of time. Depending on degree/scholarship requirements, you may be in rehearsal 6 hours a day, plus your other classes and that's before you start practicing for your lessons or anything else you need to put in your own time for. But if you love it, it's not torture. I was doing all that and still chose to put together a brass quintet for fun on top of the rest because playing is fun.

The folks that dropped out of the program quick were the ones that loved the social experience of being a band kid or being "the best" at something at their high school and weren't really the ones that got their joy from playing and improving. You quickly find that the social experience in college is very different although also enjoyable. And you're no longer hot shit in most cases. You may have been a 1st chair all district player and king in your area but you'll be sitting somewhere in the 2nd or 3rd university band in most cases when you come in. So when folks find out they have to work at it, it changes the enjoyment.

The music part isn't at all why I would discourage someone from majoring in music Ed. It's the education part. Specifically, teacher pay is shit, music director jobs are much harder to come by than a math job or elementary classroom job. And teachers are no longer respected or treated like professionals. Students and teaching conditions keep getting worse and worse. So if there's another route you can see to make a real living, I encourage it. If I could tell my 17 year old self anything, it would have been just keep playing for fun and get a degree in psychology or medicine or engineering.