Laws vary, but the practical effect depends on what's actually happening. If traffic is light, and there are plenty of passing opportunities, and cars are in fact passing without a backup, then it's a no harm-no foul situation. OTOH- if traffic is backing up, then there's a problem, and you can either solve it with some adjustment, or wait for a cop to sort it out and apply law, ie. (NYS) the obligation to ride single file to allow passing.

Also consider that it may not be related to the width of your group, but the length. As someone pointed out, it would take more time and distance to pass 8 bikes single file, than double. I stopped riding in groups on open roads years ago, but when I did, we'd break into smaller (shorter) sub groups where necessary to facilitate passing. It wasn't a question of law, since nobody knew or cared about that BITD, but a matter of common courtesy.

As a practical matter, I don't want frustrated impatient drivers fuming behind me. It increases the likelihood that they'll do something stupid, desperate and maybe dangerous. So I try to create passing opportunities wherever I can, and make life easier for everyone, including myself in the process.

BTW- for those who want to live by the letter of the law, understand that the traffic code applies to individual cyclists and motorists acting alone, not to vehicles (including bicycles) in groups. When you ride as a group in close order, that may be interpreted as constituting a parade, for which different rules may apply and/or permits may be required.