I'm not sure if I understand your question.
In my experience my son and daughter always try to challenge the position of the post. They try to check if they can move it a little bit further. I think that this is good and normal. My policy is to re-establish its original position every time I feel they try to move it in a sneaky way but I'm open to discuss the position of the post if they're straight about it and if they can explain to me why it's sensible to move it.
I can not stress enough how important have been and still are the routines, as takes away from them the anxiety. e.g. when we get back home in the afternoon:
Shoes off, prapare the books for the next day, wash, pajamas, free time, help to prepare the table to eat together, have dinner, clean up the table, free time, 9.45 in bed, sleeping by 10 p.m.
They do not have time to fight each other or complain for something they want and don't have. They know what to do in order to have have free time.
It took time to establish that, but know that's automatic and they're fine with that. I see them happy and serene. And this routine also helps me, gives me time and my attention is not always focused on me.
Do we slip out of the routine? Yes, it can happen, no big drama. Slipping out of the routine now and again does not undo it.
P.s. this routine has been built step by step with time, not everything in one go
P.p.s. I hope the meaning of the word 'post' was clear. the post is the limit, the fence.