Yes you should as some companies just erase them at the end of the fiscal year. But some companies let you accumulate a lot of sick leave and let it build up in case there is a real problem. Kind of a 50/50 thing.
If you are allowed 10 sick days a year with no excuse or loss of wages should you make sure you take them every year?
"make sure you take them every year"
I will answer with a qualified "probably not."
On the other hand, certain eye problems can necessitate taking a sick day.
For example, on a given day, you might just not be able to see yourself showing up for work.
Yes, free days off with pay. Yes, free days off to relax.
It depends on government regulations, as well ... SOME sick time is protected, where the company can't discipline you for using it ... But if you use more than that, even if you have a "bank" of it - the company may decide you're taking "too much", and discipline you in some way.