They are definetly a hassle to carry but yes they do increase the number of critters that fall under the gun.
I did not use one for years and years and killed a lot of coyotes without one, but the last couple of years I have been pretty religious about taking one withme everytime I call and have noticed a definate difference.
It is kind of like the old story about not hiding your truck. I have a good friend who thinks I am silly for going to the extremes that I do to hide my ride.
He says , hell I have had them run right past my truck on their way to the call.
My response is yep , some of them sure will.
But how about the ones that don't?
I generally carry a light decoy I made out of feathers. You can stick this is a bush out in front of you, hang it from a limb, or as I do often stick it on the antenna of my foxpro.
Any way that you use it will help. Coyotes are a creature not unlike you and I in a lot of ways, they will often see what they want to believe.
If we give them another something to convince them that this is the real deal you are one step closer to hooking him.
I have had coyotes circling me to get down wind and suddenly see the feathers waving in the breeze and turn straight to the caller. So that is just one instance where I upped the odds in my favor.
I have had them blasting in and under normal circumstances they might have just continued on through the shooting zone , instead they hung up for a second to take a peek.
Upping the odds again.
I have had a LOT of them come in and since there was a visual for them to key on they never even tried to find me sitting there, and yes that upp's the odds even more.
So yes you can certainly kill coyotes without a decoy, but if you are figuring this deal the right way , which is by the odds then a decoy makes good sense.