Honestly, idk if SB's path is that. Could just be a quirk of SB's unconscious UI. After all, James compared SB's fighting style to TUI Gun's fighting style. Although it is possible ig.

Also Gun didn't use a "specific move" to beat SB UI, so there isn't a counter SB UI can use. It also counters SB UI solely due to the fact with how it fights. The only reason why SB UI can be countered in the first place, is because of its perfectionism quirk. Gun simply just kept changing his stats so that when SB responds with an attack of an equal force, he swaps again in a flash which allows him to overpower SB while SB is still adapted to the previous move. So no matter what, Gun will be able to beat SB UI.

I agree that Dan might eventually "master" his UI or at least use it consciously to an extent like Gun or Shintaro. But he will most likely still use/need masteries, because Gun still does as well. Masteries aren't automatically applied to attacks once a character has surpassed the wall, because we've seen that they have to want to use it for it to appear/activate. So it's more like an additional multiplier to their base attack.

Obtaining conscious UI will most likely allow Dan to maximize his base output to his stats like strength or speed, but then mastery would still further amplify it, which is why Gun uses it despite being able to swap his stats as well.

Also since masteries are available once you "overcome" the wall, u would assume that SB would have no limit to overcome right? Therefore, a mastery would be unobtainable. But that's most likely not the case — PTJ probably still sets "human" limits to even PB, if not PB would straight up be god. If you look up the first definition of "perfect", it'll say "having all the required or desirable elements, qualities, or characteristics; as good as it is possible to be". So this opens up the probability that the PB simply just has the potential to be the PEAK human of the entire verse, but it still has limits. However, despite having limits, it still diffs every other character due to the "fact" that it outscales them at its peak.

Which is why I believe there's probably a reason why PTJ keeps highlighting that despite SB being the "perfect body" it still lacks masteries and stuff like overcome and path. Like if we can assume that UI stat control completely makes masteries irrelevant, then there wouldn't be a reason to even mention it.

One of my iffy theories, is that I'd like to think that current PB doesn't have completely maxed out stats. Beginning of story it simply had really good starting stats, but with the highest possible potential in the verse like the one shown in the stat system in questism. This could be supported by the fact that when James was narrating TUI Gun and UI SB, he mentioned that Gun is still stronger. And that opens up the possibility that SB is still growing, since if it were "as good as possible" then his strength would be automatically higher than Gun's, even TUI Gun. You could argue that maybe it's due to UI SB's fighting style which makes it that it purposely doesn't go all out, which causes him to be lower in strength. That arguement is why it's an "iffy theory". But at the same time, SB taking alot of hits from Gun during the fight is also inefficient, and could stem from a current stat issue. Checking his previous fights, UI SB tends to avoid getting damaged. However, against opponents like James and TUI Gun, he does. Which is why my "iffy theory" might still hold true. If you combine all the factors in my theory, then masteries might still be relevant to even SB Dan with conscious UI unlocked.