Well that is disappointing. Even as random Galaxy S5 users are accidentally receiving Android 6.0 Marshmallow early, the opposite is about to happen for Galaxy S6 and Galaxy Note 5 owners. According to the latest leaked road-map, Samsung will need to push back the Marshmallow update for the two newer devices.
The delay will likely mean a later February or early March timeframe for Galaxy Note 5 and Galaxy S6 owners to get Android 6. For whatever reason, it appears that Sammy will need to do further QC testing to make sure Marshmallow doesn't melt all over these devices in a negative way. That's probably quite a good thing!
Here's our dedicated sections for further discussions on both of these devices:
Source: MobiPicker