Workers Are Not Using Schools

[NoSpin]

I have noticed that for some reason the workers are not using the schools I built. Usually when I notice this, the jobs available double or triple the workers. But even when that comes down to 3 jobs per two workers, they are not using the schools. After a while they do, but I lose valuable time waiting for this. I am not sure if this is a bug or a feature request. What is the current priority on upgrading?

[fede]

workers don't join upgrades when they are too busy. Close to the top left corner you see some numbers, they mean free/total workers. When you overload them, the line becomes red and may show something like -5/40. The first number must be positive to let them learn!

[Zenfur]

and not only learn, train how to swim and use racetrack too. They won't waste time to upgrade themselves if you gave them a work to do which needs more of them than they actually are, as fede said.