Is working 6 day work weeks normal?

I work at an english school/daycare. Each school year, we are supposed to work a total of 2000 hours. I usually work 8 hours 4 days a week, and 6 hours on saturdays, with days off on 1 weekday and sundays. Pretty often, I work 8 hours on my one week day off, resulting in a 6 day work week.

Working an extra 2 hours on saturdays would solve the issue by reaching the 2000 hours needed while only working 5 days a week.

Is 6 day work weeks normal? Is it just stupid planning? Is it blackぽい？