i know its bad with welded in cages, when mounting the plates to the car, the good cage builders will do in weld inch then no weld then inch weld to keep some strength in the area, cus it can punch through easier if welded all around the plate.

This is not quite true. They do weld a bit then a bit more to prevent warping because the metal gets too hot to do it all at once and to get the parts aligned then they go back and finish the weld. You really need to weld all the way around roll cage parts even the brackets it's MANDATORY in most racing sanctioning bodies and they do inspect it before certifying the roll cage.

If you want to see an example of spot welding look in the photo above, look along the floor on the extreme left side where it meets the body, all those little black spots running up the inner wheel well are spot welds.