Saline locks and stopcock

I have a quick question- all RNs in PACU remove saline lock from stopcock in order to give meds. Why are the meds given this way instead of giving them through the saline lock like it is done on the floors?
.........Habit. Or maybe anesthesia likes the stopcocks off so they can leave syringes attached so they can "quickly" give meds why?

Don't know the reason but I am a firm believer that the least you manipulate a site the better off you are, do they actually leave the syringe attach?. Also are you using the same needleless systems. This should be an interesting topic.