I thought I would just like to add my comments to this part of the thread.
I recently upgraded us to Moodle 2.7.7 (this was done over Easter 2015 when Moodle 2.8 was available). The reason that we chose Moodle 2.7.7 and not Moodle 2.8 is that we will not be upgrading again until next Summer 2016. We needed a Moodle version that was still supported at that point. With Moodle 2.7 being long term support it was the only Moodle that we could go for.
From here on we will only upgrade every Summer. Assuming that 3.0 is released November 2015, 3.1 released May 2016, 3.2 released November 2016 etc. And assuming that 3.0 will have a long term support, I can already tell you that the next release we will be going to will be Moodle 3.0 next summer (even though Moodle 3.1 would be out) as, at the point of upgrading, 3.0 would be the only Moodle still supported during the following (2017) upgrade.
This can be extrapolated out and we will always be upgrading in increments of 3 to the long term support so that we are fully supported between the summer of one year and the summer of the next. If the LTS were to be 4 versions, then we probably move to skipping the 4. (I would need to do the maths on it to work it all out).
We are a large UK HE organisation and so being on a non supported Moodle version is not really an option and upgrading more than once a year is not going to happen.
(There is an argument that states, as we are upgrading in June/July, and the previous Moodle release for both the LTS Moodle and the non LTS Moodle would have been in May, then even if a bug/security issues were found during that month (May - June) it wouldn't be fixed/released until the following normal incremental release (june/july), at which point we would upgrade anyway and so it is a technically grey area). I hope I explained that correctly, I did at the hackfest. Basically being on an unsupported Moodle version for a month is mute as we wouldn't get any bug fixes for that month even if it were supported as big fixes are monthly.