It depends on whether you're talking about Bootskin (Vista), or Bootskin XP.  From what I understand, Bootskin (Vista) is really nothing more than a wallpaper.  Bootkskin XP has a progress bar and depending on your background, a trough for the progress bar to move through, which makes the whole skinning process a difficult skill, but Bootskin Buddy helps.

I gather you are talking XP.....I have seen a number of people over the years submit their first boots without a progress bar..so yes, it does work...I would assume it was a simple as just leaving it out...as they were just learning to build them.....give it a go.....though if submitting, most people like the progress bar to confirm all loading ok...and can add a bit of artistry to them...