Hi Arpit,
We normally aim for a 6 week release cycle and try to time our releases together. However, the overriding objective is to still ship stable, solid releases that we can support.
Recently, we have been doing a lot of refactoring and performance optimization work in the C core. Given the broad changes landing in this period, we explored the options of cutting a release branch a little late or just waiting out for the 1.6 release time frame to do a release. We chose the latter. So you should see a stable release landing around the same as the 1.6 releases for Go and Java. We will still support the 1.4.x releases in the meanwhile.
Is there any change or feature you are waiting for in particular to land with the 1.5 release?
Hope this helps!