Hold back one truck and give some of his stops/pickups to surrounding routes. Then load all the 'late' packages on the late truck. Maybe even use a smaller truck that will be able to get around more quickly.
I see what your thinking there.. however... customers.. wont be seeing it that way... say that was to happen...
Ill go by states as an example (just think of them as small areas)
Driver who does UT stays back, waiting for late truck... Driver who does NV takes a few of UT drops, so he doesnt have as much to take... however, that late truck also has drops going to NV as well... well; now that UT truck has to go to NV with the late parcels...
Mean while, the driver who left on time (NV), first does UT stops, but then gets angry customers at NV, because his late, and missis drop times, and even depot open times...
And the truck who is running late, well, his warehouse open times are well shot, and would almost have to come back with at least half the freight..
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If all it was, were home deliveries, and to be done till like 7pm, and your paid till you get back to depot.. in the perfect world.. would you like to start at 5am, find out your staying behind.. waiting till 10-11am, to leave the depot... then clocking off at 7pm.... thats a 14hour shift right there. (and ive sadly read alot of the messages here, and working more then 8 hours, you could watch harry potter series, and still not enough time to read the negative remarks)