Most of the time we operate out of 8,000+ runways so can be very conservative but if you always fly into Midway you have to rely on the charts to say yes or no.
My last seven years at AA I flew into Tegucigalpa, TGU, and a lot of times one degree or one knot of tailwind determined if the takeoff or landing was legal and if it was wet or dry. We couldn't put in an extra 500 feet for the kids. Why have charts approved by the FAA if you don't go by them. Either you are legal or you are not. Extreme circumstances like braking action poor to nil require judgement as to believing the charts but operating into marginal airports a standard method of operation is required. They were legal to land but I think the FAA will change the rules so thrust reverse won't be allowed to calculate landing distance like on all equipment I have ever flown.