First Biotech i worked at hadn’t established any maximum accrual, and of course as a startup encouraged people to work, not to vacation. This was all well and good, till a couple long-time employees left the company, and the full force of several factors hit:

First, of course, these people had been accruing at 3 week/year for 5 or more years.

Second, they had all been promoted one or more times, with comensurate salary increases.

Third, and probably most impactful, this was the 1980s, and 10% annual raises were common.

String all that together, and the ended up with people who had accrued weeks of vacation at as little as $10/hour being cashed out at as much as $25/hr, and getting MONTHS of pay at their terminal rate.

It wasn’t long before THAT changed! Everyone with >250 hrs was given a year in which to take sufficient time off to drop to 250, or lose all the hours over that. My crazy boss ended up leaving something like 3 months of pay on the table, and he’d hired on as a Post-Doc, and left as a Staff Scientist!