Probably a sense of casting you develop much quicker by observing others casting as well. When you continue to analyse your casting and hone it to perfection, you start to look for similarities or discrepancies in the way other people cast. And at some stage for people like us and some on here this may result in teaching novices to cast and contributing to the advancement of others. In larger groups I found you rely more on all your senses to keep track of what is happening, you see someone throw a line in the air and you know the sound it'll make before the forward loop is created, and in the meantime a subtle fluttering behind you tells you there's work to be done.Another seemingly hard thing that comes from lots of practice is hearing wind knots, this amazes beginners but they have just never used that sense in terms of casting, it's really just a slight change in the sound the leader makes.
The cherry on the cake is the amazed look you get when you tell someone fishing beside you what just came flying by and he reels in a tangled tippet, or even worse a piece of grass.