This about listings where there is no automatic reservation - which a lot of them if not most of them are that way. So applies to most cases.
There are a lot of hosts who do not respond. So you have to wait for a day or two then cancel your request if there is no response and then send a request to another place.
Website allows you to send requests to multiple hosts at once but beware if two accept your reservation you still pay fees if you cancel one. I wish there was a good alternative to airbnb