I'm by no means an expert but I've been using deer calls for 30+ years and have seen some consistency in certain aspects of calling. I think a lot depends on the deer you're hunting. I've seen places where the deer responded to calling on a frequent basis and places where the deer almost never responded...and sometimes there was less hunting pressure in the areas where the deer DID NOT respond to calling. To an extent, it would seem that some deer are almost genetically disposed to be more or less vocal than other deer, and that this trait may be localized.
I call to deer I see and I call blind. Granted you may spook unseen deer but that's just something that you'll never know. Calling to "seen" deer usually gets about an 80% response even if it's only to stop and look in your direction before moving on. The main mistakes people make when calling are in timing, volume, and movement. For instance, you don't estrus bleat opening weekend of archery season 1 1/2 months before the first does even come into heat. You also don't try to blow the reeds out of your call for volume. Wind dictates volume in conjunction with your setup and location. You start out softly and gain volume. The major mistake is movement. Once you make a call any deer within earshot is locked into your location. Dependent upon your location you may not see the deer but they may see you. After calling is not the time to scratch your butt or blow your nose. Watch for movement over the next 15 minutes. Once they hear you and IF they decide to approach they usually don't do so on the run. The exception to this might be during the pre-rut or rut. I've had bucks charge in and almost run over me either looking for the doe calling or to face the other buck in their area.
The best setups for calling have you concealed but give you somewhat of a view of the area the deer may have to travel through getting to your location...and they will cross an open field if they decide to check you out. The worst setups are in super thick areas where the deer have to be right on top of you before you ever know they're there.
The jury is still out on whether spooking a deer by calling will call shy him. If a deer busts you calling does it mean he'll never respond to calling again? If so, then it would seem that he'll live a lonely life and never respond to the real deal again...and deer are vocal. I lean more towards a deer being super wary responding to calls afterward to the point of possibly being unkillable.
I also believe that herd dynamics plays a role in "callability"; particularly concerning bucks. When an older buck has previously intimidated the younger bucks those younger bucks may be very nervous when they hear another buck grunting. This makes for some humorous entertainment calling to them while they're in the vicinity of your stand.
Calling is not for everyone and if you don't have faith in that calling will work maybe you shouldn't try it. It's not a guarantee that it will put a deer on the ground but sometimes it's the thing that can seal the deal. It's just another component in the hunter's arsenal.