I'll mention that I don't use dodeks for horary (just noticed this question was posted in the Horary Technique forum) But for natal delineation and event charts, I have found dodek considerations quite valuable; also, I use the Pauline dodekatemorion (the x13 factor) rather than the typical Hellenist dodeks (which are a x12 factor)-the book which describes the Pauline dodeks is Greenbaum's "Late Classical Astrology".
Using the dodeks is quite easy: the way I use them is to see how the testimony (again I am only referring to natal and event charts) of a planets position in the chart, compares with the testimony regarding that same planet's "ramification" point shown by its Pauline dodek: if the testimonies are about the same, ok-but if the dodek testimony is at variance with, or more illuminative than, the testimony of the planet at its "original" position, then I factor that in as an important component of my net "reading" of the planet in the chart.
Remember too that dodekatemoria (the term) has been applied to 2 seperate things:
-one, the term has been applied to the 1/12th part of signs (ie to 2.5 degree areas of each sign); other words for this meaning are duads, dwads, duodenaries
-the other meaning refers to the "jumping" of a planet (or degree or Lot) by a certain multiplying factor, to find another point in the chart relative to that planet (Lot or degree) All of the Hellenists except Paulus Alexandrianus used a mulitplier of 12 for this purpose (hence "dodec"), Paulus used a multiplier of 13: so THIS second meaning of the term dodekatemorion, does not refer to "a /12th" of anything, rather it applies to a jumping or multiplication process, to locate a "new" position in a chart, for a given planet (Lot or degree)...