At home, all of my staging tracks(HO) are on 2" centers. At the club, we use 2 1/2" centers(some folks are concerned about 'fat fingers'). The curves in staging spread out to 3" centers(just in case someone run a 'Big Boy').
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
My two HOj staging yards, which are not used as 'fiddle' yards and where rolling stock will be untouched by anything except the railheads, have tangent track on 48mm centers.
They also have meticulously laid, thoroughly tested and effectively bulletproof trackwork.
OTOH, if you expect to have to stick fingers between cars, that spacing is WAY too close.
Chuck (modeling Central Japan in September, 1964)