When I was studying I could not study longer than an hour before I needed to get up and take a break from studying.
The longer I tried to study the less focused I became and my studies and work suffered as a result.
I found that I learned much more when I would study for an hour and then take a 10 to 20 minute break and go outside or do something else.
Even at home when I'm concentrating on working on something or trying to learn something I study it for around 30 minutes and then take a break and later get back to studying.
So if you're trying to learn something and are studying try to take a break at least every hour or every 2 hours for at least 20 to 30 minutes if possible.
Taking a break from studying helps to clear your mind and you'll be much more focused and learn a lot more and easier.