So, every maker seems to have a different take on how manual shifting of an automatic ‘should’ work. I’d venture most of us aren’t mucking about with shifting the truck manually as it’s a lot of work for a very little ROI. As mentioned before, paddling the truck in normal mode or sport simply locks out or returns gears to availability. it’s kind of lazy too; it won’t take more than a single lock out request at once. That is, if you hit the left paddle 3 times as fast as you can, you get -1 - the first input does nothing, the 2nd input locks out 10th, the 3rd is ignored because it’s still working on the rather slow lockout request and downshift.
but, if you’re in normal drive mode and drop to manual, multiple downshift inputs do get accepted. Probably best not to get crazy with this, but at least it responds better than with locking out available gears.