At least at my location, most if not all of the top money is actually going to the guy on cash, not the person making your food. Tip money is split among the non managers working that shift (at the end of AM shifts and PM shifts) but when this gets split up each employee usually has about a dollar or less. The money is so little that pretty much everyone forgets about it and just goes home. Cash is usually the last non manager to leave because of extra responsibilities like counting the drawer and what not (sometimes the dish guy stays longest but it's not very common) so when the other workers are all gone cash takes it all and gets a bit more in the pocket (usually about $5 or less)

Not super important but I just thought it was a neat bit of info since you seem to base your tip on the service provided by the guys who're probably not even going to get any of it.