Leaving a laptop on most of the day

I have recently been leaving my laptop on for most of the day (usually from around 10:00 AM to 1:00 AM, and then I leave it on standby). I’m not constantly using it, though. I have it turn off the monitor after 15 minutes. I never do any resource-intensive tasks such as playing games, so I never hear the fan get really loud. I browse the internet, listen to music, and occasionally watch movies. I used to have it go on standby after 20 minutes of no use before I started keeping it on all day.

First, is it bad to leave your laptop on for most of the day? I know that PC’s have no problem with being left on all day (I left my PC on 24/7 and it never had any problems). Are laptops the same way? What kind of problems could occur and how long would it take for problems to start occurring?

Second, what would be worse, leaving it on for most of the day or letting it go on standby every time you won’t use it for 30 minutes to an hour?

Finally, I heard that you should clean out the dust from your laptop periodically. What is a good way to do this?

Thanks.

How ya doing, buddy?