How about every day for a child less than a year old?
How about more than four times a day for an eight year old?
How about more screaming than talking for a fourteen your old?
But I reject your statement. Children almost never need to be screamed at, and it is not good for them.
Child goes to touch sharp/hot/poisonous item
My likely response would be "Leave it alone" or something similar, in a considerably louder and more imperative voice than normal instruction. Why? Because the change in tone conveys importance, and the shock will institute an instant response from a child.
This is entirely separate from telling a child off for a misbehaviour already having occurred, which I agree rarely (if ever) should require "Screaming" as a method of conveying displeasure and attempting to prevent recurrence. Inevitably it will happen, because parents are human too and make errors of judgement and lack patience.
I am lost.
Why is screaming almost intrinsically "bad"?
You are trying to quantize behaviour and, sorry, it cannot be done. Would you ask how many times it is good to kiss one's mother? One? Ten? One hundred? Every time the child leaves? Just once? Uhu?