It isn't their fault the fandom is so easily confused. It is made fairly clear where Base Goku stands.Doctor. wrote:Not when people can't even agree on something as basic and important as base Goku's strength.
Even so, you could literally stay the same about Base Goku in Z. Nobody can agree where he stands. Some people believe he's stronger than 18 but not Piccolo, some people think he's stronger than Piccolo but not Kaioshin, or there's people that think his Base is stronger than Kaioshin, or people that believe he isn't stronger than any of the aforementioned characters in Base. People can't agree on Base Goku's strength in the Buu arc either.
maybe not during training during a timeskip, but that level of power jump happens fairly often. You mentioned the instance with Piccolo , but if we include all training/power jumps and not just limit it to timeskips the list is of decent size:12x is a ridiculous gap. Characters rarely get that strong through rudimentary training during a timeskip. The only exception to that was Piccolo during the training for the androids.
-Goku, Gohan, Vegeta, Trunks in their training in the ROSAT during the Buu arc.
-Goku's year training with King Kai before the Saiyans showed up which was mostly off-screen training he attained a ~20x boost.
-Goku's like week of training on his way to Namek attained an 11.25x boost.
-Goku's zenkai on Namek, and Vegeta's 2nd to last zenkai on Namek were easily at a clip of 12x
These level of power jumps aren't extremely uncommon. If Goku can gain around a 12x boost in a week then he certainly could do it in 10 years IMO. And Goku's training with King Kai was mostly off-screen and over the time skip so this fits your description to some extent.
Well, that doesn't take into consideration how much Gohan would have regressed either. Like I said, the dialogue implies Goku is probably stronger than Good Buu in Base by the time of EoZ and some consider him Kid Buu level in Base because Uub is the reincarnation and they were fighting evenly when Goku was in Base. There's little reason to believe anyone other than SSJ3 Goku is the strongest of the group by the time of EoZ.