Are you talking about Concord, MA? We have had a real problem with SOME groups of riders who are riding 2-3 across Lowell Rd. and Monument St. This is a very popular area for club rides and for people from Boston who think they are having a day "out in the country." Now, I do not agree with your friend who should be smart enough to see that there are no bike lanes on narrow country roads! But, the law says that riders should be riding single file. Whe I lead rides, I insist upon it. You don't need to be squished up against the side of the road, but if you are riding single file, it is easier to move over and let the cars pass. Police are ticketing riders for this in several surrounding towns.
Even if you are talking about a different Concord, riders should not be two abreast.