Currently labouring over the clean-ups and inbetweens of my own animated scenes, I keep wondering why hardly any of the standard works on animation deal with that process. Inbetweening gets mentioned, sometimes explained, but none of the big books on how to I've read so far consecrate whole chapters to the subject, let alone talk about techniques etc. Bluth has a fair bit on the procedures on his website's Animation Academy section but it is not, among other things, included in his book on Animation Drawing.
Cleanup is a very time-consuming process. I can animate something in two hours and then spend up to two days on getting it in "screen shape", even if it's a simple two-seconds scene for TV - so I really wonder why this difficult and exact art doesn't get more exposure in literature. Is it because it seems less prestigious than animation itself, because of the somewhat thankless nature of the work, spending hours cleaning up others' drawings which eventually zip by in less than a tenth of a second?