I run into this a lot fishing a local river that is pretty narrow and draws a lot of anglers from bass boats to jons to kayaks. Have been on the receiving end also. I'd say on average the width is 70 yards, i always slow way down to a creep to create no wake when people are in small jons or paddle boats, if they're in bass boats its almost better to stay on plane. The worst thing to do and i can speak from experience is to run up on plane and to quickly slow to an idle right at the traffic. This makes the boat plow water and can cause a lot of wake. a 20ft bass boat flying by on plane is a lot easier to handle than one coming off plane plowing a ton of water in your direction.
It can get frustrating though on a long run on a busy day and constantly going from plane to idle, plane to idle, etc.