Hello reefy86
I am making my plates and welding them at present and although I marked the holes out precisely when they get hand drilled it is possible to be a 1/4 mm out and make a problem.

so really I would say it depends on how the plates are created e.g. hand build or CNC'd or lasered will all give you different qualities.

I have made all of the Tapped holes as accurate as I can but then I have made a larger hole for a small amount of movement to allow to get as accurate as possible when setting up.so my M5 bolts have a 6mm Hole on the plates that get bolted to them.

My worry is that it might wander but I plan to do some small tack welds to keep the plates in place if they do and it it ever needs to come apart they can be ground off. but hopefully the won't be any movement.

Thanks

Rob