Fundamentally, this is a cat-and-mouse game. But I suspect that "time bomb" techniques aren't economically viable for attackers, at least not with current patterns: current attackers demonstrate "smash and grab" tendencies because they know their access is limited anyways. Attempting to wait out a cooldown exposes them to additional detection risk.

Of course, maybe the attacker profile changes over time. But that's the nature of the game.