well, he's been shown using 25 of those techniques in the manga, which is quite a lot more than most other characters. Hiruzen was said to know over 1,000 genjutsu alone, and all the jutsu in Konoha at one point in time, but I don't think he ever used more than 10. Raikiri and Kamui are his most powerful jutsu, Hiding like a mole and kage/raikiri bunshin are his best strategic techniques, it's natural that he will use them. He has stamina contstaints and as such prefers to conserve it through bunshin and hiding like a mole until he can go in for the kill with raikiri. if he's in a pinch he will use kamui. it's the best use of his stamina, that's all.