It seems like the standard around me is between 8 to 12 people. This is too many in my opinion.
I believe this is because management is unknowingly aiming for the biggest team the does not completely halts instead of seeking a team that delivers the most bang for the buck.
Personally, 8 is the largest I would have a team. At that point you should consider breaking it into two teams of 4 (even if those teams periodically recombine from the original set of 8 people).
If the two teams have to coordinate a lot and work on the same code base, is there still two teams?
To be independent, they would need to work on functionnaly different parts of the project. Not all projects have several independent parts, feature-wise.
What do I miss?