In the criminal justice system, the lawyers are educated on two separate yet equally important continents: America, which trains 20-24 year old males, and Europe, which trains 18-year old females. This is one of their stories (okay, from 2013, but whatevers.)
http://www.theguardian.com/law/shortcuts/2013/aug/11/britain-youngest-barrister-gabrielle-turnquest
I see a news story about taking university courses at age 14, and I'm like "really? This is newsworthy? That was like...my high school best friend, and I was in university by 15 myself."
Honest opinion: school curriculums are designed to give kids breathing room to do stuff like play school sports, be in a band, make mistakes and get drunk. I feel like most students I know could graduate a few years earlier if they really wanted to focus their time on academics. Now is it healthy to focus on academics over social life, and skip out on stuff like woodworking classes and track meets and school theatre productions?
The answer is no. Hellll no. Working in Japan where kids are basically at school from 6 until 6 (granted, about 3 hours out of that a day is club activity time... so sports, generally, sometimes music, sometimes more academics, depending on the kid), then going to Juku to study more and then probably get home around 9PM every day, and then they still go to school or Juku on weekends, has shown me that it's not only unhealthy but we need to stop even toying with the idea that it would be good to normalize this shit.
First of all, putting this level of pressure on the kids doesn't actually help the students that thrive under it, because they would probably be doing this sort of thing anyway (as your own experience shows). For the rest, there are basically two outcomes: you become an overstressed 13 year old with graying hair, or you stop giving a damn about your education entirely, and then continue to do so because once you quit for a while it's takes so much more effort to catch up as to be not worth it.
Add on to this that what I see day in and day out in my schools here is the toned down version of what it used to be. In the last 20 years or so the Ministry of Education relaxed the pressure that used to be put on the students because students kept killing themselves. It absolutely would not be healthy to take away that “breathing room” for outside interests, socializing, and being a kid who makes stupid mistakes.
A lot of people who thrived in school, like I'd hazard to say most of the DL, forget that school isn't just for the academic achievers to advance but also to educate those with no interest in academics or who don't have a family background that in one way or another fosters the idea that education and learning are important. Twisting the screws tighter on the education system to put everyone on the fast track to university learning at 14 would only leave these people even further behind than society has already left them, and it's not good for them and it's not good for society at large.
Should it be an option? Absolutely. Could “most students you know” buckle down on the academics and graduate earlier? Possibly. Should they? Or rather, should we be changing the way education is thought about to normalize forgoing interests outside of schoolwork so that more people graduate earlier? My time in Japan has made me go absolutely not. In this system, half of my students have just given up entirely and have no incentive to change their stance on this because they're already so far behind. 40% are still trying but for various reasons are either super stressed or depressed. The 10% that thrive would have done well anyway without this excess pressure. I'm sure most students you know could adopt a similar study schedule to graduate early but they won't be better off for it.