You don't need to do the conversion: SWA accumulates sick at 10% of what you work.
You work 100 units of pay, you get 10 units of sick. Units=units.
I've never heard of SWA asking pilots for verification of sick from a Dr. However, any month that you use any amount of sick, you lose "points" that can be applied to buy passes buddy passes. So basically you're awarded buddy passes each month that you don't call in sick.
BTW, our management tells us that we call in sick more than other airlines. It would be interesting to know which airline is the "sickest". I always assumed it was AA based on what the guys there tell me!
Our system was made for age 60. If you retired at 60 with a large sick bank, the company would pay your medical insurance until age 65. Now that you can work until 65, no incentive to retire with a large sick balance. No surprise, guys are using it to improve their schedules as there's no buy-back when you retire.