The numbers are irrelevant. The way XenForo seems to do it is that the second-point release is for new features (i.e. 1.5.0) and third-point release is for revisions. If there's no new features and they're at 1.4.9 already, they won't skip to 1.5.0 just because, they'd be more likely to have 1.4.10 and so on.