Well okay, but to take the bomb diffusion analogy, could the problem also be in the fact that every bomb is counting down super fast to the point that there's no time to build tension?
If players are dropping every fight and having to be brought back into the fight, then the main culprit is the routine dropping because it is the cause of them having to be brought back into the action. Maybe ease back on the encounter difficulty if you're mowing down PCs like wheat?
One of the worse plagues upon writing these days is not applying the correct stakes. Everything is life and death or relationship destroying. Pacing with varied stakes; some lesser, some more dramatic is the key to telling a satisfying long-term story. Not every fight must bring the party to the brink of annihilation.