The thing that changed how I think about this: which oils you use decides more than the superfat number does.
Superfat is a percentage of your total oils held back, but you do not get to choose which molecules stay unsaponified - in a normal cold process batch they are distributed across whatever is in the pot. So a five percent superfat in a recipe that is mostly hard oils behaves quite differently from five percent in one heavy with soft oils.
Which means if you want a specific character, change the recipe rather than the number:
Harder, longer lasting - more of the hard oils. This does more for bar longevity than dropping the superfat.
Creamier, more conditioning: more of the oils known for that, rather than pushing superfat up to compensate for a recipe that is too cleansing.
Bubbly lather: again a recipe question.
The practical order I would suggest: get the oil blend making a bar you like at five percent, and only then adjust the superfat, in small steps, one variable at a time.
And note that a high superfat is often a plaster over a blend that is too harsh. Fixing it at the source gives you a better bar that also lasts longer, rather than a soft bar that goes off in eight months.