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Usually every couple of weeks. Sometimes certain apps will force me to restart, even if I've had them forever. Guess I should get in the habit of doing it more often like so many other people here huh?;)
 
Once or twice a day....I know, I'm OCD... I just hate seeing my ram go from 160+ down to 80-100 (I have a lot of memory hogging apps)....so I restart :(
 
I restart mine only when needed which seems to be when I update. Once in a blue moon something weird happens and needs a restart.
 
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