Generally there is a 1-3 year payback period post graduation.
In my case it was 1 year and it was prorated. Had I left after 6 months, I would have been on the hook for 50 percent of what was paid out to me. After 1 year I free and clear.
I was lucky that 13 months after my last tuition reimbursement payment I received an offer which increased my salary 40% and gave me further responsibility. I gave my employer that paid for graduate degrees the chance to match but they were unable to.
I took the higher offer. That is how the free market works.
If a benefit is offered by an employer, why shouldn’t one take advantage of it. My beef is with folks “expecting” their employers to offer it, as though they believe it to be an entitlement.