I recall dad saying he overslept one night in the 80’s and he walked into the shed in the morning with 102 welsh lambs on broker ewes that scanned 120%. He said they were still trying to sort them the following day and in the end the whole lot went outside as 1 groupI think the key difference is that the ewes and lambs need to stay together and ‘mother up’. With dairy cattle it doesn’t hugely matter who has what as the calves are taken off the cows within 24 hours.
Sheep tend to have more than one lamb and need to bond before turnout. If no night checks were done you could feasibly end up with 10 ewes and 20+ lambs all in a heap in the shed all mismothering and needing sorting out.
I might add that the 23rd lamb was in the pet pen, I'm certain it wasn't one of the triplets but the ewes were all happy.Used to lamb 140 pairs in one big pen, needs must. One Saturday morning at half 5 (had checked about 11) I had 10 pairs and 1 set of 3 to pen up.
Took over an hour to pen up and I was still swapping the odd lamb at lunchtime but all the ewes eventually left the shed with 2 lambs.