Another one is putting someone on hold when you already know the answer as if you need to check with someone else to get approval. That tends to put some friction that prevents to much time from being wasted. Another use is if someone wants a discount. If you agree to quickly they can think it was to easy and might wonder if there is money on the table.

Do this many times in negotiation as well typically. Even if you know you will sell (or buy) at a certain price you can't agree to quickly.

(Once again all this depends on your product, who you are selling to and what you are trying to achieve.)