I don't think 14 is the maximum piesupper.
Remember this project?
https://www.youtube.com/watch?v=GBWHUdPQCH8
We flew a total of 22,000 hours building that line.
There were 4 Skycranes
1 BV107
4 Kmax
1 407
6 500D/Es
3 530FFs
1 520N
1 212S
6 or 7 Astars.
I think we got as many as 18-20 flying at the same time at the height of the project. They we spread out a bit over several miles. But you could usually see 2-4 in the air at any given time.