Guys, just bought my first Tormek. a T8. I've watched all the videos and have an idea of sharpening using only a 25° primary bevel.. and that's all... ok. What happens when that edge goes blunt... do I have to do it all over again? Surely a 30° secondary touch up bevel is more efficient? Please help me to understand the theory / strategy of single bevel only... cheers Gary!