1. In Russia I remember having eight classes a day only briefly and that quickly came to an end because having so many classes was considered to be close to child abuse. Six was the norm, sometime seven, but definitely not every day of the week. Here I had 9 classes every single day. I was not pleased at all.
2. The breaks between classes were only 3-5 minutes long in the US. Whereas in Russia they were 10-15 minutes. You can't socialize during 3-5 minutes you have to run to another class. Yes, you are less likely to "get in trouble", but getting in trouble is part of socializing.
3. Not really a problem with the schooling system, but the above two combined with living in the suburbs produces a great problem. You know you won't see any of the students for the rest of the day, unless your mom drives you to the mall or something. Socializing time is very brief during the school day, but really, that's all you've got...
Needless to say I hated going to the US school tremendously. Color me cynical, but I am somewhat surprised that there are not many more school shooting than there are now. Oh and I graduated more than a decade ago, so perhaps things have changed, but I doubt it.