Thanks all.
I know that some flowers are "open for business" early in the morning, some not 'til it gets hot. So moving from one crop to another midday makes sense. And I watched a Tom Seeley video about recruitment, (I think it's labeled "Honey Bee Democracy" on the 'tube). He says that the colony continues to send out scouts even while working a particular crop (or maybe that scouts just keep working that way). But when I see multiple pollen colors coming in (a new-to-me color today: flame orange the color of the angry emoji above), it's a lot of bees, not just one or two scouts. So Wally that makes sense that they are on multiple crops at once, but the foragers working a particular crop will keep on it 'til it's done.
Van I've seen the same thing. And I've learned that foragers store their pollen loads directly in the hive; they don't hand off to house bees like they do nectar. If that's correct, it makes me think that a set of bees devoted to a particular crop also prefers a particular place on the comb; that's pretty neat!