If you want to make user experience better, you reduce the need for user to keep track of things that you can keep track of.
You have information about number of posts I scheduled and if you want to make my life easier you can warn me at the time of posting AND later, if had 10+ posts, but deleted some and it became less than 10 you can warn me too.
otherwise, every time I delete posts, I have to check if I have recurring posts and if I do, I have to go and check how many posts I have scheduled… ON EACH PLATFORM. that’s too much work for something that can be programmed…
And because this limitation is not a must have(other services don’t have such requirement) even more reason to try make it easy to comply.
For me it makes reucrring posts unusable, because I don’t post very often.
Now I wonder what other requirements you have that I don’t expect and result in my post failing without prior warning. Is there a list?