You can't be fucking serious. Goku trained with Gohan, Roshi, Korin, Popo and Kami.
17 did nothing but mountain training. Alone.
He didn't train alone for 4 months, he spent 10 years.
Plus remember he has infinite stamina so he can keep up his training sessions for super long.
I guess when Buu shot all those beams down and killed everyone on earth he missed Lapis and all of his animals
Buu can't feel 17 so he obviously didn't target him.