You should use intel extreme tuning utility to tweak the CPU only for software/games where it actually makes sense because you can make profiles for those and leave the CPU to run at defaults for everything else.
the other thought which we have all left out is the fact that the cpu has built in "boost" technology. which will adjust the speed as it goes. single threads will speed up a single core pretty high and multiple threads will still see a nice boost if heat/power allow.
in my opinion it is not worth the time for the casual user to worry about manual oc at this point. let the built in boost tech do its job and you'll enjoy the experience just as much as fighting with manual settings and the various adjustments that have to be made based on uses and other concerns. just let the auto-oc tech do its job