Do You Shut Down Your Computer When Not In Use?

My good blogger friend told me that she never shuts down her laptop. Her lappie is turned on with more than 15 websites opened... 24 hours a day, 365 days! I was amazed when she told me this. She even obtained an extended laptop warranty from the supplier of the laptop. My desktop computer will surely slow down and ‘hang’ if I let the computer run for 24 hours. It will run smoothly again after a reboot. Do you ever let your computer run for more than 24 hours?