Here is the thing about meditation as a practice. It may make no difference whether the practice does anything on its own. It may only work because you listened to a teacher for a number of years and did what they told you, and at some point your mind said, this is real, this works. If that is how it works, then what works is the structure you built in your mind. You have nothing to lose either way, because a relaxed mind was the promise all along.
If you do not take the practice, you have to write your own from the very beginning, and you may very well have to do that. But it is the same as each generation coming along and dismissing everything we learned about harnessing fire, saying no, we are not using any of your methods, we are going to discover it for ourselves. Maybe there is a benefit in that. Maybe it is a lot of wasted time. That is for you to decide.
As for advancing in a posture, going deeper, getting stronger, finding more balance, it makes no difference how far along you are in any particular posture. What matters is that you are trying your very hardest in it, and that you are breathing your very best.