From what I remember, the last few lans I've casted at we had one PC which was in the 0 delay STV so we could fly around and watch what we want, and one PC with the program feed so that there wasn't a disconnect between casters and the stream.
It also meant that sometimes the casters could catch things and comment on them that the stream don't see, because it's impossible to catch everything live with 0 delay. Shoutout the obs though, namely gemm, sim, and kaja, because they are the ones I remember most from i-series and being beasts the entire weekends.