Do lag bolts need to be centered?
Yes, keeping lags centered in studs is important. 

The following is minimum for BOLTS IN WOOD:

Edge distance: 


Perpendicular to grain: 4 times dia. 
Parallel to grain: 1.5 times bolt dia. 


End distance:


When in tension: 7 times bolt dia. 
When in compression: 4 times dia. 


Center-to-Center spacing:


Perpendicular to grain: 2.5 times dia.
Parallel to grain: 4 times bolt dia. 


Spacing between rows of bolts:


Between 2 and 5 bolt diameter depending on l/d ratio