that is some good skill there but a lot of that can be attributed to soil type. simply, that was some good dirt to work with. i guarantee in a matter of minutes that odd shaped bucket would have been caked up with mucky clay based soil in my part of the world.
a lot easier to do good, clean fast work when everything falls out and you have a mostly clean bucket to work with. not so much when you have to shake the bucket multiple times on each bucket and eventually it's capacity is reduced by 10, 20, 30% or more because of all of the crap stuck to the in inside and outside of the bucket.