Perhaps he's been influenced by someone who gives him bad advice. For example, if someone tells him that natural talent is enough and training is overrated. Also, he could be dealing with some personal problems, like a conflict within his family or among his friends that takes up all his time and mental energy, causing him to neglect training.
Well, it could make him more desperate to catch up. He might become more self - doubting at first. But then, as he realizes his mistake, he could develop a stronger sense of determination to overcome his lack of training. For example, he might start training in more unorthodox ways to make up for lost time.
Maybe Kakashi is preoccupied with other important missions. He is a highly - skilled and often - needed ninja. There could be some top - secret missions that require his full attention, leaving him no time to train Naruto properly.
Naruto might also try to find alternative ways to gain strength. He could explore the forest around the village to find new training areas or discover new chakra - related phenomena. He has a curious nature, and this could lead him to stumble upon something that gives him an edge in his training, like a hidden hot spring that has special chakra - enhancing properties.
In the fanfic, Kakashi might neglect Naruto's training due to a variety of reasons. He could be preoccupied with his own research or a secret mission that demands his full attention. There could also be a misunderstanding between him and Naruto. Maybe Naruto has done something that Kakashi misinterprets, causing him to distance himself from Naruto's training. Additionally, the fanfic could introduce new characters or plot elements that draw Kakashi's focus away from Naruto. For example, a new threat to the village that Kakashi feels he must handle alone, thus neglecting his duties as Naruto's trainer.
Naruto's training would become more personalized. Tsunade, being a Sannin, has a wealth of knowledge. She might focus on Naruto's weaknesses more intently. For example, if Naruto still has issues with chakra control, Tsunade could design specific exercises just for him. His training could also include more strategic elements, as Tsunade is experienced in battle tactics.
He might start to rely on his friends more. For example, Sasuke and Sakura could become his main source of emotional support. He would focus on training with them and sharing his feelings, which in turn helps him to grow stronger and more independent.
In Naruto, the Jinchuuriki were often treated poorly. In fanfiction, this neglect can be explored in many ways. One common approach is to focus on the emotional and psychological impact on the Jinchuuriki. For example, they might feel isolated from the rest of the village due to the fear and prejudice associated with the tailed beasts within them. This can lead to some really interesting character development stories in fanfiction.
In a fanfiction, perhaps neglected Naruto runs away from Konoha and ends up in the same area as Yugito. Yugito, having also faced her own share of hardships, takes Naruto under her wing. They bond over their experiences, and Yugito helps Naruto to better understand his chakra nature by sharing her knowledge of the tailed beasts' chakra. This could lead to Naruto developing new abilities and a newfound confidence.
One reason could be that some fanfiction authors might focus more on other aspects like new jutsu or character relationships outside of the Uchiha clan. They may not fully understand the potential of Sharingan, which has a wide range of abilities from basic perception enhancement to powerful genjutsu. Another factor could be the over - popularity of some other elements in the Naruto universe, like the tailed beasts, which overshadow the Sharingan in their stories.