But 1 on 1 meetings are not crossing team boundaries, they are always within the team which is pretty much always smaller than 50. There's no reason the team cannot "talk to everyone all the time" just because other teams exist. But instead this communication is replaced by meetings even though the ability to talk hasn't changed.
1:1s don't have to be strictly manager:report
I'm a staff eng and have 1:1s with other managers I don't report to and my peer staff/principle engs in other reporting chains and they are some of the most valuable meetings I have to keep connected with what other teams and the rest of the organization is doing, what's going well, what they might need from me, pain points, initiatives, etc. And of course just to build and maintain rapport across the org, which absolutely pays dividends.
I do these less frequently than with my direct manager, but still on a regular cadence, typically once a month or every other month.
Managers DO cross team boundaries though, their peers are other managers. I can't talk to the 100 people in my department every week, but my manager can talk to their 9 peers, who each talk to their 10 reports.
Precisely! And this is true not just for managers but also higher-level ICs. Its ok for Senior and below to be team focused, but moving to the next level means broadening scope and that means talking with people, regularly!, outside your immediate team.
And at larger companies, teams and groups are often geographically distributed if only in other buildings and office locations.
But the initial claim was that 1:1 meetings "add value to the team". I can believe that they add value to the manager's manager, but they are not adding value to the team of the person being met with.
Startups don't have as rigidly defined team boundaries. It wouldn't be uncommon for people to take up tasks and responsibilities that would fall under some other team with a different manager.
In larger corporations, teams are insular - members aren't rewarded for doing work outside of their domain, and would be punished for letting another team do their job. Some members are so indoctrinated that they won't respond to any communication outside of their team, unless it's through their own manager.
Beautiful thought but really hard in real life. Do you talk to all members of the family, deeply, every day? Most would say no, so you need to open the spaces to do so.