If it works for you, then great, but I still just don't think it's necessary to know the grade of a hill as you're climbing it. I don't use a cadence meter either. I don't even have a computer on my bike anymore. So far, so good.
Like I said, my eyes, lungs and legs tell me what I need to know when it comes to cadence and gearing. Can't move my pedals? Shift to an easier gear. Can't breathe? Lower my cadence. Feel anxious because I have a wall of pavement in front of me? Relax my upper body and calm my breathing. Heart pounding out of my chest, out of gears and slowing to a crawl? Unclip and walk.
Admittedly, it takes some practice to interpret and react to that sensory input and to learn what strategies work best for you. Catrin will hopefully start to get that practice.
As for professional riders using those tools. Well, they get A LOT more information than your average rider gets or needs. It's apples and oranges in my opinion. We're also talking about epic mountain climbs with them. Southern Indiana hills are mostly under a mile long. How much thought and strategy do you really need? Put it into a gear your legs and lungs can handle and go. Get to the top. Rinse and repeat. Obviously it's a little more complicated than that, but not by much. I, honestly, see no reason to overthink it.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher