People often talk about an obligation -- Chiyuv -- to recite Kaddish at every opportunity for some time after the death of a relative. (Which relatives are obligated and for how long does not seem particularly relevant to this discussion, though if you feel it is please include that in your answer.)
The obligation to attend a minyan ordinarily for prayers is quantified by the time one must travel to attend: 18 minutes (1 mil) out of one's way or 72 minutes (4 mil) in a direction one is already traveling anyway. (Shulchan Aruch OC 90:16) (How to best convert between mil and minutes is also not particularly relevant to this discussion.)
Does anyone quantify the obligation to recite Kaddish? Must one go further out of one's way to attend a minyan in order to recite Kaddish than one would have had to otherwise, and if so by how much? Is there some other metric to use?