OK, so can you explain that more? This is an example of my confusion:
So far, working through the sculpting lessons, there's a lot of pieces where you mask an area you want to work on, then invert the mask. Then, your grab (or whatever) only affects what is under the now-inverted mask.
I get that 100%. Makes total sense.
But then I'll see our instructor not just masking a spot, but (for lack of a better way of putting it) masking the same spot over and over so the mask in that strip gets darker and darker as he goes over it more and more. I get that part of that is an artist sketching a line instead of just drawing it in one swipe...but does the thickness of application actually matter in this case?
HI Joe,
Yes, if the Strength (not to be confused with the Overlay) of the Mask Brush is less than 1, repeaeted Strokes will get darker and that means that the Effect of the Mask will increase.
Here I made three Mask Strokes with Strength (from left to right) of 0.25, 0.5 and 0.75. Then I Inverted the Mask and made some Layer Strokes (large Brush, Constant Falloff, to make it fair):

Nice example Martin. And it is as you say Joe, as an artist, even though the strength of your brush is at 100% and you only need to make one pass of the stroke, we tend to go over it with three or four strokes just because it's a natural motion of the wrist. So don't worry too much about it, either way is fine and neither way is wrong. Exactly how life should've been.