I also see that my SMS maps don't have interior boundaries around waterways, driveways, etc.

So-you're suggesting to go & map all those interior boundaries....should one also RE-do the exterior boundaries of that field by driving them?

Also-

Would it be necessary (=better?) to also create boundaries by driving fields that do NOT have any interior markings (waterways etc) & replacing the boundaries that SMS created by simply using it's harvest data? Say something like a square 40 that has no boundaries within it.

Thanks