I have a dual boot system with Ubuntu 15.10 and Windows 10, so I tried to fix the time inconsistency between Ubuntu and Windows by applying the above mentioned widely known fix, but even after reboot Ubuntu keeps assuming that BIOS clock is set to UTC time, while I'd like it to be set to local time to be compatible with Windows.
From some comments to the same answer linked above, it seems that I'm not the only one that has this problem.
Why this question is not a duplicate
Question Clock time is off on dual boot is very generic, and among many possible solutions has the one of making Ubuntu use local time instead of UTC. But the widespread proposed way to achieve that does not work for me and others, so I think there is a need for another question asking why the widespread proposed solution of changing
/etc/default/rcS does not work (at least in some cases), and my question addresses such need.