I wanted to share where I think I went wrong...
When I took the actual MCAT, I was really thrown of by all the clicking keyboards on the writing samples. So, I came up with the brilliant idea to use the entire hour for my essays, even though I can usually get them done in under 30 minutes. That led to a lot of time just "resting", waiting for the noise to die down before submitting and moving on.
I think I broke my groove, because on BS I scored WAY below what I was scoring with the AAMC tests. I had a hard time maintaining focus on test day, and I think it's because of the "break" I took. I would have been better off contending with the clicking!
The other 3 parts I did just fine, but the BS killed me. I'm retaking July 10, and I won't be making the same mistake of waiting out the typing. I think it's probably best if you go at your own pace; not rushing, but not dawdling either.
So, that's my experience.