There are things where suspension of disbelief is relevant, for example in Kaiju vs. Mecha fights but when it comes to character motivations, there still needs to be a logical realm where everything takes place.
'Only' 3 chapters, you should say 'already' 3 chapters. Especially for Jump Manga, we know that Manga swim or sink within their first chapters and usually already the first chapter determines if it sticks or doesn't. And because of that, Mangaka give their best with the first chapter of their Manga. I don't even need the first chapter to be necessarily good but i need to see potential. For example, Act Age didn't have an amazing first chapter but i saw potential in it. I even gave TPGW 3 chapters, because the reception here is so good and i wanted to get why. If i would give every Manga the chance that it might get good eventually, someday in the future, i would be reading so much Manga, that i wouldn't have time to do anything else.