It`s something I started a while ago. If your T-rods do not align straight up and down, when you turn the rod, it will pull the hoop towards the shell and or bend the tabs down as you tighten them. Because the other rods are in place, the hoop will not move and the hoop can warp.
Some hoops have an oval shape hole and if the rods are not aligned plumb, it makes tuning take a long time.
You can tell by laying the hoop on a flat surface to see if it lays flat or rocks back and forth. You can also tell by scratches on the shell.
With soooooo many Supra hoops made, some tabs are larger, smaller, or the hole is not centered over the insert on the lug. When sliding a hoop over a tube to tune the head, it is important that they pull straight down. Otherwise you pull towards the shell and down at the same time.
I catch a lot of flak from the members about it`s importance, but my Phonic snares have zero splay due to tolerance accuracy and design and never have trouble fine tuning.
They say I`m too anal about it. But every time I see it I mention it. Sometimes it`s just the way the picture comes out but I see it in all your rods.