Yep, the story is crazy like that. Plot gains don't make sense. They never were intended to. If you think that's bad, have you ever read Dragonball?
Krillen and Yamcha making the ridiculous leap of being around King Chappa's level to freaking Piccolo Daimao, with his youth restored, is in-freakin-sane. There's just no rhyme or reason for that kind of plot hax. Piccolo's 6 day gain on Kaio's planet, Gotenks achieving a Base power superior to his Super Saiyan power and Super Saiyan 3 on top of that to boot in 6 days is also fucking incredible. This is just shonen nonsensical power ups.