[0] Just look at Edmund McMillen (The Binding of Isaac, Super Meat Boy), Eric Barone (Stardew valley), Cardboard Computer (Kentucky Route Zero), Scott Cawthon (Five Nights at Freddy), Extremely OK Games (TowerFall, Celeste) or The Fullbright Company (Gone Home) to mention a few.
All depends on budget and quantity of course, but this is what's usually planned for from my personal experience working in that sector.
https://www.factorio.com/blog/post/fff-62 https://www.factorio.com/blog/post/fff-186
Since the 1.0 release last year Wube has published what, 2 or 3 blog entries including the 1.1 release announcement?
Why does that matter, surely it's pipelined. If you feed in RC packages to a 48h QA twice daily then after 2 days lag you're getting tested code twice daily.
I'm not suggesting that's realistic for large software houses, just that the logic seems wrong?
It would be easy to test changes to the design of Level 3 at the same time as changes to the design of Level 5, but it would be hard to test changes to the way inserters work at the same time as testing changes to the way conveyor belts work.