Bwahaha! You're not the only one who can make these puzzles, JLee!
(this is an unofficial continuation of JLee's [in]famous Word/Phrase puzzles)
The following phrases of varying lengths follow a certain rule, or they do not. If one follows the rule, I call it a Donut Phrase™! If not, I suppose you could call it something else. See if you can find out the link between all the Donut Phrases™.
"Have you ever danced with the devil in the pale moonlight?"
"Four score and seven years ago..."
"We need a bigger boat."
"I'm not left-handed either."
"Please sir, can I have some more?"
"I'm gonna make him an offer he can't refuse."
"Punch the keys for god's sake!"
"If I say it's safe to surf this beach, it's safe to surf this beach!"
"This could be the beginning of a beautiful friendship."
"Yes I said yes I mean yes!"
"War. War never changes."
"As the suns fade, so dies humanity's hope."
"You can't handle the truth!"
"Don't tease the octopus, kids!"
But here are some phrases that are NOT Donut Phrases™...
"Can't stop me now"
"I have a bad feeling about this."
"I am not left handed."
"You're the man now, dog"
"Captain Jean-luc Picard"
"just kept talking in one long incredibly unbroken sentence moving from topic to topic so that no one had a chance to interrupt it was really quite hypnotic"
"I love the smell of napalm in the morning."
"I must not fear. Fear is the mind killer. Fear is the little death, that brings total obliteration. I will face my fear. I will permit it to pass over me and through me, and when it has gone past I will turn the inner eye to see its path. Where the fear has gone, there will be nothing. Only I will remain."
"Not sure if puzzle, or just collection of memes."
"I will leave you as you left me, Kirk. Alone, at the center of a dead planet. Buried alive."
"I am the very model of a modern major general, I've information animal, vegetable, and mineral, I know the kings of England and all the fights historical, from Marathon to Waterloo in order categorical"
"I want the truth."
"You spoony bard!"
"I'm a Barbie girl, in a Barbie world."
"Bonjour, comment tu t'appelles?"
I used a program from the code golf stack exchange site (which is here: https://codegolf.stackexchange.com/) to quickly verify these phrases, but in order to do so, I had to make a few modifications to the phrases. (If you're on the right track, those modifications will seem very obvious)
Hint 2 (this is a big one):
Each phrase's status is determined by its relationship to a single letter.
Final Hint: (seriously this gives away quite a bit)
The letter you're looking for is different for each phrase. And if you compare the shorter phrases, you might not even need a calculator.
Even more Finaler hint:
When finding "the donut hole," you need to round off to the nearest letter.