That's how I treat it. Being disabled I walk all the way to the right when safe to do so in my daily commute so that I'm out of the way for the faster walkers. But I live in NYC so inevitably I get the people who still veer off and run right into me and nearly knock me over (haven't fallen to the ground yet but it's been a near thing) or seriously bruise up the arm I need to use my cane. People with their bags sticking out scrape their bags over my knuckles way more than you might guess. I'll think I'm far enough over and then they don't pay attention and veer/turn suddenly. And that's just for me as a young adult who has some sort of reaction time, I can't imagine for the elderly how bad it is.
Every time I've ever walked in a big group, we try to pair off and walk in twos unless we have a ton of space and then maybe threes. But honestly even at three side by side it makes for difficult conversation so these huge lines don't make sense to me. I mean seriously, what benefit are those people getting out of that?