Not sure if this is especially about social workers and educators but as a millennial I'm not going to spent my free time for preperations.
During the last supervision I literally told my team: “You want quality work? Give me paid preperation time at work. As a millennial I am not going to spend my free time preparing work stuff without payment :D. Shit gets ridiculous contracts work both ways. 😀
It is very common though people do it all the time.
As long as I don't get paid preperation time, no quality work. Sorry children! 😀