yes a disc MIGHT need more passes to slice and dice things up, a lot depends on the disc, slotted front disc dig deeper and cut better, the weight of the disc, (and or for 3 point disc as to drag types), down force you can add to the disc, so will how much matting material is on top and or how hard the area is
But again you can pull a disc at a MUCH higher rate of speed compared to a tiller,(its NOT a race , on any tractor, just speed are higher using a disc) a 40 hp tractor will take MAYBE a 5 ft tiller, and even trying to do 1/3 acre at a time , its a slow going and a lot of running time off motor of tractor
as for picking a field clean of rocks, that will honestly come down to HOW many rocks are in it, I have been picking rocks out of a 3 acre section for about 15 yrs now, and have about 250 ton picked so far and its still FULL of rocks LOL
actually brought in a rock picker a few times now, and some rocks are too big to even move with a D6 dozer, so there keepers in that plot!
as for the disc compacting the soil< I cannot see how that's happening,m it cuts and raises and turns over soil as it goes?
you DON"T see real farmers using tillers, just not enough time to use them!
they NO till or disc today(you actually seldom see them actually plowing soil anymore)
so, I don't think compacting soil is an issue with a disc at all!
I have used on both prime soil and very sandy, and never had a issue in the past 25 yrs using the same fields!
and disc was used on them for about 30 yrs before me being there(bought disc off farmer that used them on same land LOL)
NOTHING wrong with a tiller , but the costs, the issue's with rocks and the slower goings
if you have the TIME< the money and OK with up keeping, they do GREAT work when there going, NOT bashing, just saying
better bang for the buck in a disc IMO!