LOIs should have deadlines but most sellers and agents ignore them and honestly they don’t drive that much urgency. I’ve sent dozens of LOIs and no seller has ever said, hey can you push out your deadline as we’re still thinking through your offer. Agreed with the 5 business days as plenty. But don’t beat yourself up, I doubt that would have made a difference

Deadline is great, but mostly so you can press the point once the deadline is passed. "I need a ETA on your response, otherwise I'll unfortunately have to void the LOI, as it has already passed its deadline" type of message works great. On the flip side, if no deadline is sent (as I've done a couple of times - by mistake), the seller has no date to base on and this can lead to a prolonged response date. Always put a deadline - no downside