There is an EASIER and more common sense reason for better pairing construction. Safety.

Anytime there is a late night (local) time departure with a > 18 hour layover and early morning (out station) departure, you have a circadium rhythm swap for the crew. Despite best efforts, we all know how hard it is to prepare our bodies for a redeye flight only to have to start flying the next leg 6-9 hours later than the previous leg. We have been a fortunate group w/ not having an incident based on pairing induced fatigue.

I propose there should be a rule for ALL multi-day pairings that the show times of the days following the first day cannot vary by more than 4 hours. For instance, if a pairing show time starts at noon, the show times for EACH DAY of that pairing following must be between 8am and 4 pm. This would, of course, eliminate odd timed layovers of 24 hours and the need for pilots to try and adjust their rest/sleep habits by 8+ hours within a 24 hour period.