Hello Bill, welcome to the Village, it's great to have you as a new member. I'm wondering if, you could do a bit of introducing yourself, just so that we can get to know you a bit better? What's your hobbies, where do you live and are you married, that type of thing? We don't need you to tell us your life history, just a tid-bit of your goings on. There's no rules stating that you need to introduce yourself, and you don't need to if you don't want. But, if you do, it makes it easier to get to know you and treat you like we know you. The previous posters have pretty much answered your question, there'a not much to add to what they've posted. Personally, I think it's just a matter of practicing. But, yes you are right in your suspicions, if the blade is to large, it's very hard to cut a 90* cut. With some blades, you just need to have a waste area to cut into, there's no way around it. I cut using the Flying Dutchman brand of blades, I can comfortably cut a 90* corner with up to a #5 blade without stopping. If I'm using a larger blade, I may have to stop and spin the piece of wood. With any blade over a #7, I look for a waste area to cut into because it makes things so much easier.
Len