I’m always amazed when I go to a church where there are 3 or 4 priests listed in the newsletter...and only the celebrant will serve Communion.
Priests used to spend all Sunday morning in the church, either celebrating Mass or assisting the other priests (this was before concelebration, btw) - and then they’d have the big Sunday dinner at the rectory, usually followed by Scotch provided by the pastor...
But that was a different world, I guess.
Our parish is a Dominican priory, so we often have a preacher (in black robe), who reads the Gospel and gives the homily, in addition to the priest who offers the Mass. They don’t usually concelebrate, but after the Agnus Dei, a second priest will come out from the sacristy to assist with distribution of Holy Communion. One priest on each rail. Occasionally, a priest will have to do it himself, but even then, the altar rails (and distributing under only one kind), keep things moving pretty well.
Sometimes there are Masses in the ancient Dominican Rite. Absolutely wonderful!