The brass needs to be trimmed to the same length for the most consistent crimp. A lot of work for some applications. I like the Lee FCD for auto loading pistols that I don't want to bother trimming. Sometimes seating and crimping separately gives the best results. I do it that way more than not.
If I have a bunch of brass I want to to load for casual use, but I don't want to trim it, I'll segregate by length and readjust the crimp die for each length.
