I can't quote anyone authoritative, but it is my understanding that steady speeds during break in are not going to get the piston rings seated properly and lead to oil consumption, thus the recommendation to vary the speed. It is hard to do but not using the speed control would probably be a good idea.
Years ago, driving a 77 Volare, I got stopped for speeding by a Ohio State Patrolman who was driving a Plymouth. I explained that the engine was burning oil and I was trying to vary the speeds, and we began exchanging sad stories about Chrysler engines. I did not get a ticket!
John
Years ago, driving a 77 Volare, I got stopped for speeding by a Ohio State Patrolman who was driving a Plymouth. I explained that the engine was burning oil and I was trying to vary the speeds, and we began exchanging sad stories about Chrysler engines. I did not get a ticket!

John