I need 4 holes on the wall for a bracket mounting, the 1st hole can be anywhere, but the 3 other holes need to follow the 1st hole and need to be extremely accurate or the screw will not fit, from my experience its difficult for me to drill the hole so accurate, can have only +- 1mm variance for mistake only for each hole.

How to make such accurate drilling ? drawing circle on the wall is easy, but once drilling starts, the drill bit will some how "move" a bit if certain part of the wall is harder, how to prevent the bit from "moving" ?

you need the hole to be same size or slightly bigger than the "pipe" on the plug, and when hammer it in, loosen the nut, the hole need to be deep enough for the entire "pipe" plus the head of the screw to go in. i am installing these too, i purchased item that come with low quality anchor wall plug, and im changing them to something bigger, more reliable, its not that difficult to put them in. oh btw dont make the hole too big, or the wall plug will be useless.

condo has weak walls, cant compare.

i heard last time ppl use human skull from a very stupid human in construction so that the final product can last longer, i need your skull, so i that the wall plan you describe can last longer.

jibby say you wont.

i was thinking bout this too, drill the 1st hole, mount it tight, then from the bracket hole, start drilling, but will damage the drill bit and make even more noise as the bit hit the metal instead of just the wall.