I have seen that it is hit or miss in the SAW. I have had times where I was able to drop 2 four day trips and sometimes 3. It all depends on how quick you do this at the beginning of the SAW, but I believe it also does depend on thier grids. Most of the time if you want to get rid of something, they are going to want you to give them a mutual or better trade.

Like CRJ said though, just call planning and they will tell you what and when. A nice approach helps.