I recently looked at the squad mode section of the core rulebook again and spotted something I had forgotten. Squad mode improvements are solely based on the rank of the brother who initiates them. The reason I had forgotten this is that killteams in my experience are an even playing field when it comes to xp and rank.

But it did get me thinking about NPC squads. Rites of Battle treats tactical marines for example as a group of rank one. What if that group had a veteran sergeant with rank four? Suddenly bolter assault looks a lot deadlier. It means that veterans would have even more value for their expertise just beyond their own personal killing ability.

I think you answered your own question.

Less of a question, more of an observation. Could be useful for GMs who want rules for NPC squads.