I've done 7 hours of cutting in a day. Cleared a large block of land.
It would take 3 days for a novice like yourself to clear that block.
People with limited experience like yourself should not give advice when you don't know what you are talking about.
Guards are great for beginners but all the experienced operators I know take them off. The machine is better balanced, lighter and cuts quicker as you don't get tangled as much.
The video explains how rocks will likely go in what direction and other reasons for removing the guard. You should watch it as he is a pro giving you free advice.