Remember, you can use the 2 shifting paddles simultaneously.
Yeah. You can change both the front and rear derailleurs at the same time. Up to the big ring, and onto a larger cog at the back; down to the small ring, and onto a smaller cog at the back. Up on one, down on the other.
I learned using shifters on the down tube. I couldn’t change them simultaneously. Well, not without crashing. The paddle shifters on the bars are designed so that you can shift easily without taking your hands off the handlebars. When I first began using paddle shifters, I continued to use one at a time, and didn’t realize the benefit of using them both at the same time.