I seriously, don't know how they manage to do it. It's really insane.
Well, first, think how good a lot of their iTunes stuff is when they're on the show. They probably take a day out of their schedule to record most of these songs. Plus, some really amazing people do all the arrangements. They aren't perfect recordings, but many of them are pretty darn good.
What I mean is, they're used to doing it fast, and doing it amid doing a lot of other activities -- and also, they're really good artists who can get it right in only a few takes. I think the Idol training helps them a lot, also.
Seeing as I like a lot of old music, I sometimes laugh at people taking a year to record an album. It just seems crazy. Frank Sinatra recorded a whole album in a week or two, just singing live in the studio with an orchestra, no need for multiple tracks, tons of mixing, etc. And those albums are still classics.
But since people today often write their own songs, I can see them needing more time, to write.
Now, someone like Kris, who had the goal of writing the songs on his album, and who flew all over the country collaborating with various people, had a much harder time, for that reason. Adam just had to go into the studio and sing the songs people wrote for him (for the most part), and so have many of the other idols. They were on tour, so that made it harder, but they're singers, after all, and they've competed on AI, so just laying down the tracks for 12 songs shouldn't be all that tough. I really think the songwriting-plus-singing route would be the hardest.