For whatever the worth (if any) I would suggest that the updates will continue to be done as they have been since the monthly cycle began many months back, and would continue to contain a mixture of fixes/enhancement/features.
I have the lifetime updates, and see no difference whatsoever in the maintenance that I get with that, versus what I was getting prior to getting the lifetime updates option. They don't release multiple sets of maintenance for Sonar Platinum for a given drop - it's just 1 set of updates.
I would also add that I REALLY like the monthly approach to the maintenance, going back to X2 and X3 for comparison. We would pay for a version, then over the course of the next year get a couple of maintenance updates and then that would be it until the next version would come out. That left a long time in between updates, where unless a hot fix was released - we would have to deal with whatever we got until the next one came along.
With the monthly updates, they are prioritizing fixes every month, so that in theory - they would address the most needed fixes more quickly - I have never had a more stable Sonar environment than I have had with Platinum, and LOVE it.
Bob Bone