Many software packages claim to do the trapping correctly, but nine out of ten better litho pre-press experts will say that so much depends on equipment variations that they'd rather do it themselves. I say okay. So I look for ways to avoid trapping all together. First, have no touching colors. Solid black over color.
Colors are transparent, even black.
If the dark colors overprint completely there'll be little difference to notice. The best policy is to ask your printer to see samples, or check the paper sample box. You'll find that solid overprinting will show slightly if it runs into a non-printed background, or if it is printed onto very absorbent paper. Utilize kindred color families that share one or more color values, when building with process colors. Trapping was no a problem because the dark color overprinted all, eliminating the chance for problems.