Many autistics you may have seen will seem to have had their own pet perseverations. Some like to listen to certain songs over and over again, others like touching certain parts of their body frequently and so on. This is often referred to as motor loops. I have had my fair share of these over the years. These typically start off meeting a sensory need but continue unabated if not intentionally addressed.
There are differing opinions on whether these need to be addressed or if we should be left alone. I have personally been open to being redirected, as hard as it is sometimes, if we are collaboratively doing something and/or if someone is investing time in me. My parents have always respected this need of mine and I do get a lot of time to do my own things.
One specific example of a motor loop for me is the swing. Swings helped me get regulated originally but became a safe hiding spot during years when I struggled with serious dysregulation. I used to be on the swing for hours with someone pushing me. It gave all of us peace for those few hours, but not something I absolutely needed to do. Looking back at this now, it served its purpose.
No easy answers when it comes to motor loops. Lots of hard work to break some and an unapologetic family outlook to let some be. Hopefully science will provide more answers at some point in the future.