Are timers good for flash sales?

As an e-commerce manager, I'm exploring strategies to create genuine urgency during flash sales. I want to understand whether countdown timers actually drive conversions or if they're just another gimmicky tactic. My team is skeptical about implementing timers, worried they might seem manipulative or reduce customer trust. I need concrete insights into how timers impact buyer psychology, sales performance, and overall customer experience during limited-time promotional events.