I was just rewatching some random episodes, including "33", the very first episode of season 1. The theme of the episode centers around exhaustion, and they make a point to show that Boomer was holding up far better than people around her, even jokingly saying that maybe she's a Cylon, which is actually true.
That said, I also noticed that two other characters are holding up really well - Saul Tigh and Galen Tyrol. While everyone in the CIC and on the flight deck are barely standing on their legs, some are openly sleeping, but those two were still both literally and figuratively running around and doing their duties, Tigh even skipping his turn(s) to sleep just so Adama could sleep instead.
Boomer is our confirmation that exhaustion gets to Cylons far, far slower than humans. Aside from Boomer, only Tigh and Tyrol were holding up relatively well. Does that mean their identities were planned from day 1?
Also, Saul Tigh was featured in a Season 2 blooper reel as "Number 13"