It depends on what kind of whois info you are talking about. For mandatory fields like nameservers, it's done in SECONDS (at least for .COM and .NET). And these days, any registrar which does not submit changes to the registry right away (in less than a couple of minutes) shouldn't be in the business at all. Even for other fields like Admin Contact email, I don't see how and why it is not updated in batches of less than a few minutes. Anything longer should only be occasional problems; or else, you may want to transfer your domain away.