What an Idiot!/Anime and Manga/Dragon Ball

You'd expect that he would also acknowledge his son Trunks' warnings, considering that he knows a great deal about Cell, and annihilate the evil android while he still had the chance and prevent the destruction of the world as well as thousands of lives. Instead he beats the crap out of Trunks and then allows Cell to transform into his ultra-powerful One-Winged Angel form because of his massive overconfidence. Cell proceeds to promptly beat the crap out of Vegeta, Trunks, and anybody who stands in his way at that point, threatening the entire world with his power. You'd expect that from that point on they'd actually split any magic bean into two so that they have double the limited supplies of magic beans without having any drawbacks. Instead no one splits a magic bean ever again... You'd expect that during their second year-long-training Trunks and Vegeta entered they'd be SSJ all the time, thus not only becoming FPSSJ but they'd be if not stronger at least equally strong as Gohan and Goku. Instead Vegeta and Trunks completely forget about the benefits of training as a SSJ all the time, thus even though they trained double the time Goku and Gohan did, they were far weaker. You'd expect Krillin would take this opportunity to use a pointblank Kienzan on his blinded enemy, ridding the universe of a great evil once and for all. It's not like he could have forgotten that he has that technique, considering he was attacking Frieza with it several times in a row mere seconds earlier. Instead Krillin shouts at Vegeta to take the opportunity to blast Frieza... even though moments earlier Vegeta blasted Frieza with all his strength to no effect. Krillin is actually surprised when Vegeta doesn't take the opportunity. Let's see... technique that is guaranteed to accomplish nothing versus technique that could be a one-hit kill, regardless of the user's Power Level... Gotta go with the flashier one. You'd expect Krillin to bust out a surprise-attack Kienzan, slicing Recoome in half while he was busy with the attack and eliminating yet another member of the Ginyu Force, as well as making some headway toward not being regarded as a joke by the fans. Instead Krillin slams Recoome's mouth closed mid-beam, accomplishing little more than knocking out his teeth and severely annoying him. You'd Expect: Goku to save Trunks and Goten, not only giving them access to the amazing powers and abilities of the only other Super Saiyan 3 in existence but also given them a formidable 3 to 1 defence against the most powerful creature in the history of the universe. Instead: Goku saves Hercule and Dende: an act which literally had no foreseeable benefit. Goku had full knowledge that Porunga was still alive which nullified any benefit they would have gained from Dende and Goku had absolutely no way of knowing Hercule was going to rally the people of the Earth for his Spirit Bomb or summon Fat Buu to save their collective asses (a situation that would have in no way been relevant if they had access to the exponentially stronger Gotenks.) You'd Expect: all of the characters to only use incredibly powerful, explosive ki blasts, since they are the only attacks that have a chance of doing anything. Instead: nearly all of the characters continue to waste their time and energy using hand-to-hand combat, or blowing holes in Boo's belly, or doing some other kind of damage that is known to be meaningless. Then they act surprised when it doesn't work.
 * Dragonball Z, Vegeta, while effortlessly defeating Semi-Perfect Cell, acknowledges Cell's last transformation.
 * In the Frieza saga Goku splits a magic bean in two parts, so that Gohan and Kuririn can both have their part. They are fully recovered, even despite eating just half a bean.
 * The Full-Power Super Saiyan means that by remaining transformed as a SSJ for extended periods of time the users can conserve their energy consumption much better than any other form of SSJ, thus they become stronger in training than any other form of SSJ would make them. While the FPSSJ users Goku and Gohan exit the training room in this state Vegeta and Trunks notice how genius this kind of training is, Vegeta even comments about this.
 * According to Word of God, Krillin's Kienzan technique is capable of cutting through anything (the only times it failed to cut through its targets were in anime filler scenes). Now, let's look at a certain point in the battle with Frieza: Krillin has just blinded Frieza using the Taiyoken.
 * Earlier, when Recoome was about to use his Recoome Eraser Gun on Vegeta, Krillin moves up for a sneak attack on Recoome.
 * The Earth is seconds away from being destroyed and Goku has time enough for only one choice: use Instant Transmission to save Hercule and Dende or use it to save Goten and Trunks.
 * Majin Boo is immortal, has infinite energy, and can completely regenerate as long as any of his atoms are intact. In effect, any attack that doesn't completely obliterate every single atom in his body is meaningless.