Pitching question

[Dakota]

Is a back swing legal? Yes.
Is a stop necessary to have a back swing? Yes.

So, where does the rule state how long the stop at the back of the back swing can be?

And, if you claim "immediately" means "infinitesimally small", explain how the word "immediately" clearly does NOT mean that in the look back rule.

The purpose of these pitching mechanics rules is to not have the batter be deceived as to the start of the pitch and when in the pitching motion to expect the release. Was this deceiving anyone? (e.g. Did she do this sometimes or all the time?)