I honestly believe that your gains increase proportionally with your power level.
Let the joy of love give you an answer! Check out my book!A lot of Goku's time on Kaio's planet was probably not spent training to increase his powerlevel, but rather trying to master two complex techniques that were vital to defeating Vegeta.
I don't know whether Goku could've reached Vegeta's powerlevel in the time he had. Maybe he could, maybe he couldn't, but even if he could, Vegeta would just go Oozaru and trounce him that way. So... It was probably the right call.
But we really can't use Goku's increases to judge how much Piccolo would increase.
If Piccolo's power did shoot up far more than Goku's did in less time, I can always just headcanon it to having a sparring partner at roughly his level to train against (that being, well, himself, using Multiform).
edited 27th Nov '15 1:53:20 PM by IAmNotCreativeEnough
himitsu keisatsu seifu chokuzoku kokka hoanbu na no da himitsu keisatsu yami ni magireru supai katsudou torishimariIt's not like Piccolo even knew how strong Freeza was before he got revived. He just assumed he could handle it because he had gotten a bit stronger. And, of course, he was totally wrong.
And I didn't think Piccolo growing giant even increased his power. It just made him bigger. Like...he could try and squash Goku, or something. But that didn't even work. There's a reason he turns back to normal partway through the battle. He realises it doesn't help at all.
edited 27th Nov '15 4:30:48 PM by LOLypop1224
The *Legendary* Super Saiyan is motivated by a crying infant! He is a literal giant f***ing baby!
Which, as I've mentioned before, I find hilarious.
When I first read the manga version of that I was surprised by how little time he spent actually pretending Piccolo could change anything. That the original anime took like an episode or more of pandering to him, and even Kai half of one, is even more hilarious.
edited 27th Nov '15 4:32:57 PM by LSBK
Not necessarily. Again, he has no idea who strong Vegeta was back on Earth. He just knew that Vegeta was stronger Nappa.
Let the joy of love give you an answer! Check out my book!Actually yeah. Vegeta couldn't hide his power, so when Piccolo sensed his power, he should have sensed all of it right off the bat.
So if he thought he could beat Frieza when he knew Frieza was stronger than Vegeta, he must have either been stronger than or thought he was stronger then Vegeta when he went to Namek.
One Strip! One Strip!Vegeta was relaxed and not using it, yes, but his 'relaxed' state at that point was his max power of 18000. Remember, the characters in Dragon Ball don't power up to fight, the intentionally lower their power outside of fights. This is yet another one of the reasons why the filler scene of Super Saiyan Goku actually feeling a rock that was thrown at him by Krillin was dumb as shit, and also part of the reason why Resurrection of F relied on a plothole for its dumbass climax, both because there's exactly one person in the universe who can sneak up on Goku, and her name is 18 (and probably 17 too but let's not mention him) and because Goku needs to actively lower his power; if he's off guard, he's probably not actively lowering his power.
In other words:
The Goku that fought Freeza had a PL of 3.000.000 as a base. If you caught him completely off guard, sleeping... Unless your PL is >3.000.000, you're still not going to be able to harm him, no matter what you do.
And if that fucking Laser thing could've harmed Goku, then someone could sure as hell have used it to murder Freeza who, unlike Goku, can't sense ki and would actually be susceptible to that kind of assassination.
edited 27th Nov '15 6:46:07 PM by IAmNotCreativeEnough
himitsu keisatsu seifu chokuzoku kokka hoanbu na no da himitsu keisatsu yami ni magireru supai katsudou torishimariI just realized the rock thing was a Call-Back to a scene from the early days of DB. Kid Chi-Chi didn't believe Master Roshi was who he said he was when she first met him, so she decided to test his legendary reflexes by chucking her helmet blade at him. It lodged itself right in his head.
"It's liberating, realizing you never need to be competent." — UltimatepheerI dunno. If I'd been the one to write that, I would've had that scene be about Krillin throwing random stuff at a sleeping Goku who just never notices it, with increasingly weirder objects.
himitsu keisatsu seifu chokuzoku kokka hoanbu na no da himitsu keisatsu yami ni magireru supai katsudou torishimariI should also note (unless the anime changed it) that Roshi did see the blade coming. He just made the mistake of trying to block it with his staff instead of dodging it instead.
One Strip! One Strip!There's a "DOOOOODGE" joke in there, but you'd all see it coming.
"It's liberating, realizing you never need to be competent." — UltimatepheerI thought the point was Goku lowering his power level while in Super Saiyan. I thought that was the entire point of the Mastering Super Saiyan concept.
If Goku lowers his power level by enough I can only assume that he can feel pain.
I also assume that you can lower your power level and relax. Relaxing doesn't automatically lower your power level, but.
And the reason I assume that is because Vegeta napped on Namek while still trying to hide from Frieza.
edited 27th Nov '15 9:04:06 PM by unnoun

Regardless, it did happen.