Well my shop guarantees for either a week or 2 weeks, depending on the purchase. The animals that are known to be delicate and would be easily lost if improper husbandry were a factor only get 1 week. The hardier species usually get 2 weeks.
So like an ETB would probably get a week, but a corn snake would probably get 2.
1.0.0 Ball Python Omega
1.0.0 Amel Corn Bob Dylan