1. Always. I used to never use it but I learn from my mistakes. 2. Long term I have much smaller losses with using S/L than without using one. 3. Depends what time frame I'm trading. In 1H-5M somewhere inbetween 40 and 10.
I agree with this. There is too much emphasis on psychology, and not enough on understanding the market itself, devoting a lot of time and effort to become good at technical and fundamental analysis etc. You either get all kinds of terrible ...