This is actually a sneaky thing to do. My old firm used to give 10 sick days a year, and everybody used 8 or so. Then they made it “unlimited” sick time, which really wasn’t unlimited, and everyone took fewer since nobody was sure of the point where you attracted too much attention.
At one company I worked at for years, we could donate personal, sick, vacation time to co-workers who really needed it since most of us didn’t use much of ours anyway. That was very pleasant, none us ever hit the use-it-or-lose-it wall.
My company is like that. They don’t have a sick day policy. If you’re sick, you’re sick.
I got kidney stones my third week there and was out for a few days. I think in the ensuing 5 years, I’ve missed one day. Therefore, if I get sick and take a week, nobody is going to think I’m taking advantage.