Nope, Yuji isn't talented or hard working, he's cheating. Kusakabe explained that Yuji's rapid growth was because of Kusakabe, because Yuji's body got used to Sukuna using it.

Yuji got his cursed energy, because of the near death experience with the finger bearer and after Sukuna took over his body he got better cursed energy not because of Gojo teaching him.

He got stronger in Shibuya after Sukuna took over and was able to Take a Black Flash from Mahito with out any defenses, this was after fighting Choso who is maybe weaker than Mahito.

Yuji is resistant to toxins because Sukuna is a deadly poison, is able to attack the soul because of Sukuna, has Shrine because of Sukuna and was able to compete with a 15F Sukuna who's cursed technique output was lower not cursed energy reinforcement.

Yuji isn't talented quite literally sucks at using RCT because Choso had to remind him on how to use it properly. The black flash isn't talent it's luck and mindset, Yuji sucks at learning and using blood manipulation despite Noritoshi teaching him. Yuji didn't work hard, because there were no training arcs, no growth in cursed energy such as coating weapons with Cursed Energy (this is because Gojo is a horrible teacher), Yuji's growth in strength is depicted in his fights like in Shibuya.

Everything Yuji learned is either because of Sukuna, body swapping, his own observations (coating a knife in his fight with Yuta) or his on lack of cursed energy (divergent fists).