True, you do need to make the pitcher comfortable. We have one who calls her own game and doesn't get signs. Since DD doesn't know what's coming, she just stays behind the center of the plate and does her best. (I could be wrong, but even though that girl is a good pitcher, I think she ends up with more close pitches called balls than the other girls.)
I believe the idea is not to set up clearly outside of strike territory, but rather so that the inside/outside pitch should arrive somewhere in front of your body rather than to the side. Game this fall, I saw DDr shift out and then catch a low and outside pitch with Coach Weaver's C position. Blue had shifted slightly with her, stood right there and watched it come in (it was dang close). He looked down at her arm and hand, paused and said, "Strike." I really believe that knowing the pitcher put that pitch exactly where she intended sold him on that one.
I was also at a game one day when a catcher was staying right behind the plate, letting her arm go wherever to snag pitches and then bringing them back into her body. Blue was mad as heck, muttering all kinds of stuff and calling just about everything a ball. That's rare though, the umps usually have more patience than that.
No signs for the C???? How can that be a good idea? The catcher HAS to KNOW what is coming.