Had one that let you accumulate one sick day per month, but if you didn't use them they rolled over. First few years I didn't use all of them, and then one year I used thirteen sick days in one year (most of them for kids home sick from school) and got lightly scolded for it in a performance review.

I wanted to say "Bitch why do you allow rollover at all if you don't want us using more than we can possibly accumulate in one year?!" Looked it up in the contract and it said nothing at all about maximum sick days usable in a year. Of course if you have sick days left when you leave, they pay out at one third, but FUCK that, I earned that time, I'm not taking a one third payout. And they didn't EVER give merit raises for those years I barely called out sick.

So the next year I took even MORE sick days, and afterwards made sure not to leave any unused, even if I wasn't sick, because fuck them.