This is what 7 feet looks like.
Yes, I know people generally don't have the luxury to do this. And I know 5 feet is enough. And I know if you're crunched for space it is better to put less space between the tables and more space on the outside where people hang out.
But for those who have some space, there is a point that is I think under-appreciated.
You might think
five feet is enough
six feet is better
seven feet doesn't buy you much over six feet
But the third one is wrong. With 7-feet a player on one table can almost always walk by someone shooting on the other table -to eye up a shot, get back to the chair, rack the balls, get to the next shot.... When there are matches on both tables, things go considerably faster with 7 feet.