I don’t agree with this - certainly not as a blanket rule. Yes, you should be as prompt as you can be when replying to buyers. That’s why the 24 hour rule exists. But regular immediate responses can actually imply that you’re either not busy and/or desperate for work. If I’m messaging a professional freelancer, I’m going to assume that they’re spending most of their time working on client projects, and will reply to my message when they stop to look at their messages, rather than expecting an instant response. A positive, professional reply within a couple of hours should be more than suitable.
@muztre - like others have said, there’s nothing you can do. In an ideal world, clients would come back to let you know if you’ve been successful on every inquiry, but that simply doesn’t happen. In fact, I’d go so far as to say it’s rare that someone comes back and says “Sorry, we’ve chosen someone else.” I reckon that’s maybe happened to us 10 times in 3.5 years? Most of the time, you just never hear from that prospect again.
It’s just how it is with Fiverr. But, if it’s happening with most of your messages, then you may need to work on your communication skills, as it’s possible that you’re not answering people’s questions sufficiently enough to be able to secure their business.