Originally posted by Gideon
When you are explicitly stated to have mastered all that you've learned, it does. 😉
Where exactly is that stated? We know that he was "believed" (which begs the question, by whom?) to have mastered nearly all known powers, forgotten ones, and created new ones at his leisure, and we know he studied (studied, not mastered) the Force in all its guises, but where is it explicitly stated that he mastered absolutely all of the knowledge that he possessed?
As for your "assessment," it's really not anywhere near as clear cut as you'd like to think.
Firstly, knowledge =/= mastery. It's your knowledge of the Force, and your control over it that defines your mastery over it. His studies in and knowledge of the Force, as I've almost always acknowledged, is certainly more encompassing than that of anyone else in the mythos, but his control of the Force hasn't shown to even come close to some of the other characters in the mythos.
Darth Bane for one, displayed the ability to fill up a room capable of housing hundreds of students with a storm of force lightning with a single burst of energy, all while still a Sith initiate, and not an hour after having learnt the technique in the first place (a display of mastery with the technique that rivals Palpatine's best showing after decades of growth and refinement with it).
He's shown himself capable of energy absorption throughout all part of his body rather than just his hands (such as his face and back), the ability to store it for long durations of time and protect his internal organs from it, and the ability to redirect it across an entire planet (which would require that he be able to sense out the landscape across the planet with the Force in the first place).
His telepathic resistance is of such a high level that Kaan's manipulations -- which were capable of keeping the entire BoD under control, which included multiple notably powerful Sith Lords such as Kas'im, Quordis, Kopekz, and Seviss Vaa -- "had no more effect than a rusted knife scraping against the hide plates of a Halurian ice-boar."
He was capable of resisting one of the deadliest poisons in the Galaxy (something that the dark side is explicitly stated to not be very effective at), and this after having been unaware that it was in his body for most of the time until it began to maximise on its deadly effect.
When faced with eight Sith Umbaraan Assassins who had trained their entire lives to use the Force to shield themselves in it, he showed himself capable of completely revealing there presences with a single wave of intangible dark side energy.
His mastery as a seer is so great that he can see "far into the future," and he can apparently do this at will whereas all other seers in the mythos have only ever had visions come to them in situations beyond their control.
And most notable, of course, is his telekinesis, which had shown itself capable of absolutely crushing the likes of the highly ranked and powerful Quordis, breaking through his defences "as if they weren't there," the ability to affect vast areas of landscape with simply force pushes, and eight years into his career, five years before his current state at the end of Ro2, the ability to use it on the subatomic level, a level of control that's completely unprecedented and surpasses that of any other by about ten miles.
His mastery has certainly shown itself to be greater and wider encompassing than Palpatine's (he's displayed mastery in energy channelling, Force defence, telepathic resistance, Force sensing, precognition, telekinesis, Force lightning, resisting poisons; and the ability to use the Force on the subatomic scale, and channel it across entire planets) and if you want to get back to Force knowledge, which is only half of the puzzle anyway (if that), he possesses all of Revan's knowledge via his holocron (which surpassed all of the teachings in the Korriban archives, and possessed both knowledge in the dark side and light side), and had soon learnt all of it (as directly stated), as well as that of Freedon Nadd, which contained all of Sadow's knowledge, with which he had even longer time to learn from. While he's had far less time to learn from such knowledge than Palpatine has, his improvement rate has shown itself to be astronomically greater than that of anyone else, as demonstrated with his early lightning display, as well as with the above mentioned time it took him to learn the entirety of Revan's holocron.
Palpatine on the other hand hasn't shown mastery anywhere near as widely encompassing as Bane, his control hasn't even come within lightyears, and he's only ever demonstrated the ability to use the Force over such distances with the aid of Sith focusing crystals and the like, such as in Sithisis (which would imply that he relied on such devices). His knowledge base is certainly far greater, in many ways, but unlike Bane, his exact magnitude of knowledge hasn't in any way been defined at all, and he certainly can't be said to have ever been able to learn an entire holocron's worth of knowledge, let alone one the size of Revan's.
Conclusion: Bane has demonstrated the unaided ability to channel the Force with a range that Palpatine has never himself demonstrated, control that eclipses that of any other display by miles, wider encompassing mastery (in areas such as foresight -- which Palpatine was explicitly stated to be useless at; the reason why he relied on the Prophets of the dark side -- and obscure areas such as telepathic resistance), and while his knowledge base certainly doesn't compare, it's extremely formidable in its own right, and unlike Palpatine, the magnitude of knowledge he's learned from his sources can be properly defined. By virtue of existing information, Bane possesses the superior mastery of the Force, and by no small margin.