I have followed the directive that each course should be on its own map, for certification. (If someone wants to supply a combined map to the RD, that's fine - it doesn't appear on the USATF site.)
The combined maps I have rejected have seemed to be too cluttered. There are a few that would work on one map, but many seem to have Start or Finish in a different location for each race, and Turnaround descriptions are different.
If we said it was okay, then courses which should not be combined, would be. That would cause more issues, trying to explain why some can, and some can't. Also, do we limit it to two? I had one submission that was Half-marathon, Marathon, 50k, and 50 mile, all on one map. That was cluttered. All just followed the same out-and-back route, but the two longest went back past the Finish, to another turnaround. Took too long to isolate each course.
Even when done by hand, if someone does the longest course first, then zoom-copies the shorter segment and makes the second map, I don't see that as being too hard. Digitally is a piece of cake. So, I don't see "effort" as being a good argument for combining (how many???) courses on one map.
We are paid to do the measurement. If we give a discount for measuring them simultaneously, but no discount for mapping, if multiple maps are involved, the RD still gets a discount, and will likely be happy. I just don't see a good reason to combine onto one map, for the cert and posting on the USATF site. EAch course has its own cert, and should have its own map.
My opinion.