I find combined PTO is great as long as you have enough of it. I get 35 days PTO and I don't have a problem taking a day off when I'm sick.
Now if I only had 15 days PTO....
Now if I only had 15 days PTO....
Compounding this is the fact that I can only carry over 5 days per year, so at most I can only use 20 days in a calendar year). In a few years my PTO gets a bump to 20 days a year.