I think of OS differently than an "exercise" program. I approach it as play, exploration and experimentation.
Not as therapy. Not through a lens of dysfunction and correction. Not as mobility or flexibility training. Not as warm up for other activities. Not as its own discipline (such as yoga).
I approach it as play -- something to do for its own sake because it is fun and feels good to do. I approach it as exploration of and experimentation with movement. I don't look at the categories and principles (changing levels, moving the head, contralateral movements, limbs crossing the centerline, etc) as restrictions or instructions, but as inspiration to explore. If you look at Tim's videos on the OS YouTube channel, he exudes this vibe of play and exploration. He's constantly coming up with different variations, with only the directive to "give this a try."
I think that Tim sometimes oversells and overemphasizes the theory behind it and the idea of emulating and recapitulating the development of movement skills in children, and the idea that we were "meant" to...whatever. I don't necessarily buy it, and largely ignore it. To me, it's completely beside the point of why I use OS. I generally like to have a scientific understanding of what I do, or at least a theory/hypothesis that I have confidence can withstand a little critical thinking. With OS, I just don't care. When Tim starts talking about the vestibular system, or babies and how we were "meant" to move, my eyes glaze over. But when he comes up with another way to rock, crawl or roll around, I pay attention.
I just look at it in terms of black box cause and effect. It feels good when I do it, and when I do it regularly, I feel and move better. Specifically, my posture is better, my shoulder mechanics are better, and I feel both looser and more tied together overall. And I think a key phrase there is "do it regularly." I don't find OS practice to create dramatic immediate effects. But with enough consistently accumulated reps, "all of a sudden" everything feels better, and whenever I stop doing it for a while "all of a sudden" I don't feel or move as well.
As I've gotten older (now 56) I feel like my movement vocabulary has shrunk. To maintain movement freedom (a term I like better than "mobility" or "flexibility"), I have to make time to explore movement variety. It's easy to get locked into certain patterns through a combination of training and lack of non-exercise play (even playing basketball regularly, there are patterns I naturally fall into that are hard to deviate from).
For most of my life, I had very good movement freedom (mobility/flexibility, whatever you want to call it) -- until I didn't anymore. It sneaks up on you over time. As Ernest Hemingway once wrote in a different context, it happens "Two ways. Gradually and then suddenly."
I actually started doing a lot of Scott Sonnon's mobility stuff many years ago (anyone remember Zdorovye?), but didn't do it consistently because I didn't think I "needed" it. I didn't -- at the time. But looking back, I DID need to be doing it then, so I could still move that way NOW.
Nowadays, I find OS works really well to help regain some of that lost movement freedom in a fun and enjoyable way. It doesn't pathologize your current state (whatever it happens to be). It doesn't require special expert instruction (you can just watch a video and give it a try). You don't need to conform to precise technique standards. You just need to crawl, roll, march, and skip around -- play, not train.
"It might reasonably be maintained that the true object of all human life is play. Earth is a task garden; heaven is a playground." (GK Chesterton)
