Being a larger seed, oats seem to be fine to broadcast, then disc, then run the cultipacker.
I've plowed, then made one pass with the disc, broadcast oats, then disc'd them in, soon as you get a good rain, seems to make nice stand. With the drill we were planting 3 bushels per acre, so I would assume you could calibrate your broadcast spreader to do the same, not sure what happens if you over populate oats for a grain harvest, but assume it would need additional fertilizer. The drill drops fertilizer, so theres another pass to make. Oats like nitrogen, but you can't overdo it, gets tall, then leans over, might get a downed crop (see last photos- some is down) which I have seen, and we recovered by using those spring loaded guard extensions on the grain head of the combine. It would be less passes if plowed, primary tillage, then disc'd. or whatever is used for secondary tillage to prepare the seed bed, then plant with a drill and have the cultipacker behind that when using the drill, less compaction, vs broadcasting, we ran the cultipacker separately, always wanted to make a hitch off the drill. I suppose there is some validity with making less passes = less compaction, better root structure, hard to really say what will happen where, with what soils, but worthy of mention here and consideration in the field when planting.
In the photos I posted, these oats were broadcast in, my food plots did not get rolled though, (2nd to last photos) just disc'd, as I did not have a cultipacker, but do now. Last photos were of harvest the following year, these were drilled in, sprayed for weeds and fertilized again, got tall, but doubled the straw yield exactly from the previous year. Germination looked good, not sure about waste, but one year they broadcast seeded the field here, and just rolled it after, and I could see a lot of seed on top, that should have had more cover, they sprout roots on top with enough rain and moisture and it will tap the earth, but if it was disc'd lightly then rolled, germination would have been better for sure. Might have been some waste with seed when they did it that way.