Re: Do you keep your PC on 24/7 ?
Once a month or more often.
I used to be an uptime junkie. I've had several systems which had been up for over a year, with my longest ever being just over 2 years on an actively, frequently used server for a business.
Doing this is the same as setting your system up for reinstallation if you let it wait long enough. Eventually you will have accumulated enough software updates that your important services will no longer have the same configuration. They are running with the config you had a year or two ago, and that is NOT reflected by the config file on the disk and possibly you might have a new version of the server sitting on the disk, with a cached copy in memory.
I just found (a week or so ago) a remote server that had been up for a year and a half. I rebooted it, and sure enough nothing worked anymore. Took me a day to fix it.
I'm inclined to leave my system running, but I find that any more than a month of uptime you risk a broken system when you do shut it down, and the longer you wait the more severe the problems will be. If you wait over a year, it will NOT be just one thing broken.
Help stamp out MBR partition tables. Use GPT instead!