The difference between the first leg of the day...and the last leg of the day..
"Oh..we'd better pick our way around this..."
"Ahh...F-it..yeah, we'll take direct..."
I am, of course, joking. The reality of the situation is that until you know the makeup of the atmosphere and what exactly you are poking your nose into, you almost always err on the side of caution. We crossed that front four times today, and the first time, we went around the worst of it, sampled the edges, and found the air to be fairly stable (not much uplift, no lightning, and only light chop). So you sort of learn the "character" of an airmass. It doesn't mean it can't change, but you get a pretty good idea of tops, turbulence, icing, lightning, and precip if you fly through it a few times. Worst we experienced would be classified as light turbulence. Atlanta and Indy controllers were top notch tonight...