Yesterday was my first experience with recording a CD (with the Mountain Ayres, Midd's madrigal group). It was alternately nerve-wracking and extremely fun, and I've certainly learned a few things in the process. For example, and in no particular order:
14 hours is a long time to spend working with anyone, even (perhaps especially) people you like quite a lot.
In the time it takes to discuss whether you should record a song again, you could have just recorded the song again. More takes in general give better odds of success.
The songs you think will take the longest will in fact be the most painless. Similarly, the songs you expected to plunge to the utter depths of flatness will mysteriously stay (nearly) on key, or even more bizarrely, go sharp.
Recording is not a time for treading lightly and avoiding hurting people's feelings. I personally would like to know if I am messing up, and would be happy to return the favor. A good track is worth stepping (gently) on a few toes.
Sometimes the song just isn't going to be perfect. Corollary: it is really hard to settle for less than your best.
Altogether, I thought it was a great experience, even if I felt like I'd been beaten over the head with a music stand at the end of the day. It was amazing to spend an entire day singing, and I can't wait to see how it all comes out.