Posted 29 April 2017 - 10:01 PM
I tied commercially for many years, and kept my scissors in my right hand as you describe. Picking up & putting down scissors can slow down production tying, so, it's good to learn. However, not everyone will be comfortable tying like that as the other replies have shown or have the need to tie quickly.
I also use scissors with large finger loops, as it's important, that the scissors are both comfortable in your hand, and can be moved around without putting them down. The only way to know if it's something you'll like, is try it & see. Just keep in mind that it's best suited for volume tying, and in particular when tying in an assembly line type procedure where you're sticking to only one or two steps at a time. The person you saw likely has developed that habit, so it's become a natural part of their tying.
I only do it now when I'm tying a lot of the same type of fly, and I still tie in that assembly line type manner. Otherwise, I pick up & put down my scissors as I need.