Thanks for giving more detail - definitely sounds like I need to turn the health down a bit then!
I originally envisioned hopping in, opening some crates, killing a few enemies, and then at that point needing to make the decision to extract early or push your luck to get some more loot but run close to the time
So tuning down the enemy health a bit should skew it in the players favor a bit more to squeeze in a couple more kills before having to leave (hopefully)!