The tradeoff in one line
The clock makes the game harder, and loot makes it easier. Every chest sits on the wrong side of that equation for a few seconds.
You are always spending time to buy power. The question is whether the power is worth the time.
What a chest costs
A chest costs gold to open and seconds to reach. The gold wants you to kill monsters, and the travel wants you to cross the stage.
Both payments come out of your clock. A far chest costs more time than a near one, even at the same price.
The fast stage
A fast stage keeps the difficulty bar low. The monsters stay soft, and the teleporter boss is easier to survive.
The cost is power. Fewer chests mean fewer items, and a thin build meets a rising clock with nothing to spend.
The slow stage
A slow stage floods you with items. A rich pile can carry a weak player through a hard fight.
The cost is the clock. While you loot, the director keeps raising the threat, and the next stage starts even higher.
The practical rule
Compare your kill speed against the clock. If monsters still die fast, you have room to loot. If basic fights are turning long, leave now.
That single check beats any fixed time target. It reads the run you are playing.
Continue with stage routing or see the threat side in the director and difficulty.