In Dragon Ball Z ep.54, (this is during the Namek Saga), the Elder Guru unlocks Krillin's sleeping potential, and so Krillin reaches his full potential, at a power level of 14,000. By the time Krillin fights Goku who was being possessed by Captain Ginyu (ep.71 I believe), he has a power level of 22,000, and by the time the Z fighters fight Android 18 (ep. 135 I believe), Krillin has a power level of 450,000!
If Krillin's true potential was really unlocked way back in the Namek Saga, then how could it have risen, wouldn't that mean that his true potential wasn't really unlocked? His power should have either been as high as it became at the start, or it shouldn't have been able to rise. Is there an in-universe explanation for this?