that is the OTS, official tapers section at the Hampton Coliseum 10/8/89 when they performed as The Warlocks. Before my time as a taper.
There are never sections like that anymore since:
a. many clamp on one stand due to space restrictions and the prestige of having a massive tree.
b. that was still analog days and pre internet trading, so the need for many 'masters' existed, due to the deterioration of the source as the clones bred clones and more head noise was introduced by the machines.
c. nowadays, every digital copy is essentially a master