With helicopters and the rhino, center is simply where you trim it to be.
But without any of the axis tom-foolery that the return-to-center trimming dcs has for spring sticks.
Axis scaling etc is more for when you have more physically limiting situations. For example, if you pull back on the stick as far as you can, but you hit your chair and you only reach 80% output, you can scale down that part of the axis by 20-25% and get full range without also grinding down your nuts.