But if you are working on a signature campaign then try to make your post time interval long so that it can help your campaign and the banner promoted to be visible on different time of the day.
People are really doing that??
Imho, that doesn't make much sense to me and I don't think that it even work the way you think or helps the campaign you are part of. Instead trying to time your answers and spread it over longer period of time you should focus on the quality of your posts and everything else is less important. That of course doesn't mean that you should write 5 posts in 10 minutes, but if you are actually putting some effort in your posts you won't be able to that anyway.