Ladders and Density training are both steeped in fatigue management. It's only natural to combine them once you realize this.
When doing both, I often use a reverse ladder...usually like a 3-2-1 or a 5-3-1 kind of thing. It's probably just a mental trick, but in the last few minutes of a 20 minutes session, it's easier to go 3-2-1 than 1-2-3, at least for me.
They do take time to do. Especially if you are allowing close to complete recovery to do so. I generally only use them with 1-2 exercises at a time for this reason.