I've gone in both of the directions mentioned here: totally custom-made shirts, and shirts off the rack simply tailored down. My problem is that I have a thick neck, and when I buy a pre-made shirt that fits my neck, the rest of it is a tent on me.
So all my dress shirts must be tailored or custom-made. Frankly, I can be happy with either solution. The jacket rarely comes off in public, anyway, and if the formal dinner jacket does, I'm still wearing the vest, which never comes off.
It helps that my tailor keeps my fitting on file, so they can make my shirt without my even being there. Likewise my bow tie size is kept by a Vermont company that makes them all for me. (I absolutely detest one-size-fits-all bow ties with a buckle, that's visible when wearing a wing collar)
I simply phone them up, and they make my tie to my collar size on file, depending upon what kind of collar I'll be wearing. A wing collar bow tie for me is 1/2" bigger than one for a turn-down collar.
I highly recommend this company, who've also made my formal vests on occasion, though I think they're no longer offering that service to the general public.http://www.beautiesltd.com/