Jueno is a great zone! Always plentiful pulls and NM's roaming freely! However...you do need to have a sleep job. You will get links and to be able to get all the TE efficiently without sac pulling them all a BLM or RDM is very nice to have. I usually do that zone trio with my brother and a good friend. THF/NIN/BLM is what we usually take and most nights leave with at least one to two 100 pieces.
Back to the OP, it's random. We got a shield 1/4 runs and it was from a link we got killing a TE. Just gotta keep at it and take the advice above. Easy to find a friend or two^^
/jelly
I have killed those NMs about 100 times now and I'm 0/100. We trio THF DNC BLM. We still make 150 singles, but never any hundreds :(