An example - A planned 4 sector day from STN to DUB and then Malaga.
On the first sector it diverts to Shannon and crew wait for the pax to be bussed over - lets say a 3 hour delay. You'll only be paid for the first 2 sectors and another crew cash in on the Malaga.
Equates to 8 hours (ish) work for 2 hours pay.