Many countries have this system and the usual effect is that the duration people are sick for is magically never less than 2 days. It's dumb policy.
And there's an unlimited number of sick days. As long as you have a doctor's note, you still get paid, up to some ridiculous limit at which you might have to get government support instead.
15 is the average. I use it to reassure people that it's okay to take sick days, and not one of those rights that no one dares to use.
Usually, employers ask for a doctors' note after 3 consecutive sick days, but the reason for the sickness remains hidden from the employer. The note just gives a time range, nothing more.