I would say that aside from possibly your drill-driver, the circular Saw is one of the handyman's most oftentimes used tools. But as useful as this tool is, it can also be very dangerous (duh). A blade spinning fast sufficient to slice through wood like butter is no toy to be played with. One thing about these Saws is that they have this annoying guard that keeps shootin' back over the blade every time you pull it out of the work piece.
So although dangerous, many woodworkers tie the guard up so that it's constantly in the "up" position. This also means that when you place it down periodically in in the middle of use the blade will make direct caress with the outside you place it on. This is not good for the blade - not to mention what would happen if someone were to accidentally trip over it and trigger the switch! -Talk about a saw that's got Legs! (The solution for this is to park your saw upside-down or blade-up.)
So as is often the case, you have to reduce a slice of your protection for a scoop of user-friendliness. I personally prefer to take this risk over dealing with that nagging guard. Having said that however, a friend of mine recently had an urgency while using a circular saw and it was a good reminder that you can't ever "let your guard down" if you know what I mean. He was a bit shaken but ok.
The 2 of us were working up on a rooftop laying roofing panels and it just so happened that my friend was scared of heights. So he had to sit and work cuz he couldn't bear to stand and be field to one of his worst nightmares. Anyway, sitting while using a circular saw is not advised - for safe bet reasons. Your arms don't have much reach which means your legs come to be your work bench - bad, Bad idea!
He was lucky as he walked away with only a small nick near his right knee. I don't even want to fantasize what Could have happened. Being comfortable and procure in your work environment is an foremost point as this not being the case played a part in causing the accident. Good luck with your circular saw use and remember to pay attentiveness to the points mentioned above. In conclusion, make an educated decision on either you'll use your saw with or without your guard - the manufacturers put the guard there for a reason.