No, you can’t make General statements like that, “professional “ work is not standardized, there is not one canvas size, but many different sizes. I am a designer, I have done all Kinds of professional work for decades and can give you many examples for both height and width. In fact from my experience canvas sizes are wider more often than not, and widescreen displays are getting more and more popular for that reason. Height is ONLY more important when the ratio of the canvas vertically causes empty space, otherwise the opposite is true. When you say height is more important You can only speak for yourself, not for every “professional “ in the world. I prefer it at the top, because My canvas sizes are mostly wider than the Ipad, and the position at the top is perfect.
You can ask for custom settings to move it to the left, but don’t say it has to be there for professional work. That’s not true
BTW, you mentioned print, why? Print sizes also are wider than the iPad, so the toolbar at the top is ideal. Look at this A4 canvas, so you see how width is more important in this case: