Well, unlike what this guy thinks, if you wanna use a spirit board, you don't wanna have your salt circle go all the way around the board. How the fuck are they supposed to use the board if you're keeping them out with a protective circle? You wanna surround yourself, but leave the board just outside your circle. Your arms'll be outside the circle when you're using the board, but you can pull yourself in when you feel unsafe.

[i'd like the record to show that there is no canon basis for this being how ghost summoning works in ghostbusters but here i am anyway bullshitting everything]