Trigger "jobs" usually are done to lighten or shorten the SA pull which would be used for deliberate fire. Depending on the gun, the DA pull might be lightened also, but the design of the gun usually prevents doing much more than smoothing things up. Also, remember that the hammer fall is shorter with the DA pull and you don't want to affect the reliability of the DA, since that is what you would rely on if the gun were needed.
Jim
