I think the biggest issue with blades is this: all wood is slightly different so 20 Viscarias will all feel slightly different. A pro will get sent a batch of blades 10-50 and will try many and keep the ones they like, the ones that feel "better" to them.
One time I got to try a blade that Xu Xin had tried and rejected and it felt pretty darn good to me.
With rubbers, usually when you buy a rubber, it was sitting on the shelf at the retailers for....we don't know how long. When the pros get rubbers, they are likely fresh off the press, they have just been manufactured.
I have a friend who used to be sponsored by Butterfly. I got him to get me T05 and T05fx. I paid cost for the rubbers. I had a friend who had just bought the same rubbers from Paddle Palace. Our blades were similar. We swapped setups to see how each felt with brand new rubbers. The rubbers on my blade felt alive and juicy, really good, really responsive. The rubbers on his blade felt tired and old in comparison. There was no question that he felt the difference as well.
So....yes and no. But certainly, a top pro can also get a TT company to customize blade construction, ply thickness, gluing process, head size, handle shape, for a blade. Like, I think Xu Xin, at least back then, when I tried the rejected blade, used a blade with a notably larger head size than the actual model of the branded product.
Also, with rubbers, a top pro could get a company to tweak sponge hardness and top ply hardness to their liking. I think Timo Boll was noted for using T05 that was a little harder than the standard fare.
So, some of this does also depend on the pro you are talking about. And some of the issue is their access to the equipment so they can try and choose. Some has to do with them choosing slight modifications that naturally occur. I think those harder T05s TB used were a little heavier and Butterfly just searched for the ones that fit that category and gave them to him. Rather than it being something that just was not available to anyone else.
But it could have been what caused the development of T05H.