Canon put the control ring in 3 different positions on different RF lenses (front usually, middle on some, back on some). It's ridiculous, and an embarassment to think that a company like Canon could have such a bad design decision green lit all the way through to production. I tried to set the control ring to a function I might want to change, and then found that it started changing that function when I didn't want it to since there are too many similar rings on a zoom that you can't help but occasionally mis-set it. I have set the control ring function to NONE - not only is it worthless to me, but it's worse than worthless as it just gets in the way.
Also, in zooms they put the zoom at different front/back positions on different RF lenses. You get used to it on one, and it's reversed on another - also ridiculous.
On the good side: The RF 100-500 f4.5-7.1L happens to be my favorite lens. Why? Because 1) it takes such beautiful photos and 2) it covers the focal range (from 100) up to 500 and I use it for birding (or "cat-ing") almost always at 500mm. But on the bad side: The zoom is on the front of the long lens, where I don't want to support the weight of the long lens, and they make you have to release & re-position your hand to fully zoom between 100 to 500 - that's a lousy way to design a lens.
If you think about it, it's even worse than this. If you buy a control ring adapter, your control ring is "way in the back" which could be considered a fourth position!