When I had stuff nicked they did the 11mm chain, not the Squire lock, although they could get to both. I’m still using the lock but have sidelined the chain for something thicker. In fairness to the chain itself the scrotes used (and ditched) some decent Irwin Record 42″ bolt croppers, I doubt anything of the thickness would have stood up to that. They had to cut both sides of the long link and the blades were heavily marked so it put up some fight.
Personally I don’t like ground anchors because it means the chain is at ground level and scrotes can use teh long arms of bolt croppers and floor as leverage. If the chain is up high enough (and can’t be pulled down) then they can’t lever so easily.
IMO, having been burgled, your and other’s POV may vary.
Having been burgled I now don’t rely on the chain. I’ve fitted heavier ones but they’re still in a garage. The house and garage are tied into one alarm so my hope is they won’t have time and cover to work on whatever is securing stuff at “leisure”.
Burglars and thieves, scum the lot of ’em.