I use copper planes ("fills" or "pours" depending on specific software being used) for all boards. They greatly improve connectivity to signals connected to the planes (usually ground) and can work great as a 'built in heatsink' for certain parts. However, their spacing does look pretty small on this board. Appears to be in <10mil and maybe about 6mil spacing for that one. For the issue with the star washer hitting into the plane - that was somebody's design or implementation flaw. The pad should have been larger or the star washer should have been smaller or an insulator (e.g. mica insulating washer) should have been added.

The only thing I would recommend on this one --> square 0.025" posts are not great for mounting this sort of thing. If you don't think so - ask ANYBODY that has worked on a Gottlieb System 80B CPU board. Use round 0.019 pin strips and plug these into standard DIP sockets. Costs a bit more but very well worth it.