Why do you have to take your own personal time for medical appointments or the flu?
Some companies give all paid time off (PTO) in one pool. Other companies have different pools for vacation, "floating" holidays and paid absence. I've had both experiences.
I'll actually start with the second. Vacation is set by the employee, and scheduled/approved well in advance. "Floating" holidays are sometimes designated by the department, sometimes given to employees to schedule like vacation. (Ex. Engineering schedules floating holidays for 4th of July, Thanksgiving, and the last week of December. Manufacturing is an every day sort of thing and they can't have everyone gone for whole weeks at a time, especially when the end of the year is crunch-time, so Manufacturing lets employees set floating holidays like vacation. Everyone gets equal scheduled time off. Paid absence is what you use for dr appointments, sick time, etc. It is in "theory" unlimited. However, there are policies like if you miss more than 5 days or whatever, you need a medical note, and if you rack up a certain amount, they will look into it a little more closely.
Some companies say, "Look, if we are actually
going to try to limit the paid absence thing, why not just say so? And why make them categorize their absence? Either they are here working, or they aren't here and aren't working." These companies offer PTO which is all types of time off. This has its advantages, because if you schedule your appointments outside of working hours, or use flexible timing to take a long lunch and then stay late, you can actually schedule those hours to extend your vacation by quite a bit.