One of the best pieces of advice I received for MTBing was from an older, long-time rider. I was struggling with finding the rhythm of a local trail. It was a constant battle for me to gear right through its odd ups and downs (which are all short both ways), and I constantly felt like I was fighting the trail with shifting and such. He told me, "Find a gear you like on that particular trail, stay in that gear, no matter how hard it is to punch up the climbs and how much it feels like you're spinning on the decents." Worked like a charm to get me to better understand the rhythm of the run.The same reason some guys prefer to wheel in their XJ on 31's vs their buggy on 42's.
The trails you ride on a carbon full sus 12 speed bike are completely different on a SS hardtail. Your focus is different, lines are different, effort is different. I tend to focus on cornering and more direct lines, because I know if I lose speed, I can't just pedal to get it back.
The worst thing about SS is you're always in the wrong gear.
The best thing about SS is you're always in the right gear.
Ride it now with shifting, but a completely different understanding of the patterns. And I don't shift as much or as widely as I used to.