I’m seeing recipes for chicken breasts that want it butterflied or pounded. Some want both. 
Others say cut the tender out of the breast and then butterfly.
Whats the point in making a breast so thin? 
I know it cooks a couple minutes quicker on a electric grill. But, 2 min of cooking time isn’t that big a deal.
Does it taste better when you butterfly a breast? Or pound it? Why chop off the tender?
Youtube has a basic butterfly how to.
this one removes the tender, butterfly and pounds. 
Look at a chicken breast, and observe how the thickness varies. This means that the thinner parts will cook more quickly than the thicker parts, so you might burn the edges while the center is still underdone. When you pound it or butterfly it or remove the tender, you are making the thickness more uniform.
One reason is to get the breast more or less the same thickness so that it can cook evenly. Otherwise, it’s very easy to end up with the thin parts overcooked by the time the thick part is done.
You do this when you want a thinner piece of chicken. With faster methods of cooking you can end up getting the outer part of the meat tough before the interior is done with a thicker cut. You can also make rolled dishes like cordon bleu with the thinner cut. Pounding also tenderizes the meat somewhat, and evens out the texture. Simply butterflying the meat before cooking can cause the meat to seperate at the slicing lines and have an uneven texture.
My SO has been doing the pounding thing a fair bit lately. IMO it makes the meat much more tender (because you know, ya beat the heck out of it to pound it flat). And because it is so thin you don’t have to cook the heck out of it, so it tends to stay more moist as well.
Of course a crappily cooked and prepared pounded breast is probably worse than a perfectly done normal breast but I do think a pounded one gives on the chance to make things better.
Try it a few times (just be sure to not OVER cook it). You might be pleasantly pleased.
It sure makes it a lot easier to lay a slice of prosciutto on it and wrap them around a bit of cheese before you bread the whole deal. 
Pounding out a chicken breast makes it a lot easier to eat in a Chicken Parm sandwich.
I always butterfly my breasts before grilling for the purposes already mentioned. They cook faster and more evenly, without any parts getting overdone and hard.
I’ll try butterflying my breast next time. I didn’t realize it made so much of a difference.
America’s Test Kitchen/Cooks Illustrated does the butterfly+pound method when making stuffed chicken dishes of all sorts. They even go so far as to trim the resulting pieces into measured rectangles. It’s way easier to stuff by rolling instead of jamming stuff into a tiny slit. It also cooks eavenly and looks pretty after being sliced into serving portions.
Put your breast into a Ziploc bag to pound.
If ya’ has ta ask, ya’ ain’t ever going to know…
Maybe I’m not a good chicken breast butterflier, but when I butterfly, I end up with a big piece of chicken that is still thin on one end and thicker at the other. IOW, I don’t find that butterflying makes a difference as far as making the breast uniform thickness. I wonder if I should be cutting out the tender prior to butterflying.
peedin, the objective of butterflying isn’t to make everything exactly even (which isn’t possible), it’s just to make it even enough. If the thickness difference is large enough to be a problem the way you’re doing it, try slicing a smaller area (don’t try to slice the whole breast, just the thicker part).
Pounding the chicken breast thinner not only makes the cooking time for all sections more even, it also decreases the overall time required too cook it.
That means you can cook it at a high temp, quickly searing the outside to seal in the juices. Nothing worse that a dried out piece of chicken breast.
What do you (pl.) mean when you say “tender”?
They’re also called chicken fingers. The tender or tenderloin is a thin bit of muscle along the spine that’s loosely attached to the breast.
If you take a whole chicken and break it down, the tenders are somewhat self-evident, but you generally won’t find them sold at the grocery store - there’s enough demand for them by restaurants that the processors reserve them for commercial use.
The “tenders” (short for “tenderloin,” as far as I know, although it’s not a real tenderloin) are pretty commonly available here. They’re usually cheaper than a whole boneless, skinless chicken breast, for whatever reason. I buy them for stir fry all the time.
This is what I came to share. I have thought myself brilliant for the past few years because I thought of doing this.
Additionally, if you didn’t pound the crap out of the bag, you can dump your marinade in afterward, and only use one bag.
I don’t think this is universally true. I see tons of them for sale in the grocery, and I buy them frozen all the time. They’re more expensive, of course, but like our pal pulykamell says, they’re fantastic to use for stir-fry.
See, at my local grocery, they’re less expensive. Like I said, I’m not sure why.
Another benefit to butterflying or flattening is that the chicken to other ingredient ratio in a bite is more consistent. On it’s own chicken breast doesn’t have a lot of flavor so big thick pieces are less yummy to eat since you’ll get to much chicken and not enough sauce or whatever in some bites.