I take Asacol - six in AM and six in PM. I have been taking that dose for about two months and it has worked really well for me. I like taking the meds only twice a day. I miss a lot less dosages that way. I think there is a lot of room for experimenting though, when one is taking 12 pills a day. Maybe you should try it on a different schedule and see if it helps.
Asacol not been perfect though. I still have some UC symptoms everyday including diarrhea about once a week, occassion blood clots and mucus but, I now never "go" more than six times a day which is so much better than before. The only problem I have with it hasn't done much take away the pain.
Also, If you have a lot damage going on in your colon it may take longer than you think for the meds to help your body heal it all.