I've studied quite a bit of psychopharmacology, so I think I can shed some light on the OP's question. Until pretty recently, antidepressant discovery was largely trial-and-error, or random luck/observation. Only rather recently have chemists begun designing antidepressants by first figuring out what the molecule should look like, and then make and test it. ("Rather recently" = ~20+ years, but recent compared to other medical advances). Even now the bulk of new-drug development in this form entails things like selecting a particular optical isomer of a known drug, or modifying like one moiety not thought to be the main driver of the drugs effects.
You'll notice that new antidepressants kind of come in waves—like prozac came out, the shortly(ish) thereafter, a bunch of other SSRIs came out. Same thing, more or less with MAOIs and tricyclics. Developing from scratch a drug that has certain desirable clinical effects is really, really hard, and usually requires some luck.
As for combinations of drugs achieving a desired therapeutic outcome, this is really hard for researchers to study, for statistical reasons that I'll spare you unless you're interested. When psychopharmacologists start down the polypharmacy road with a patient, there's a lot of guesswork and trial-and-error. The good ones can often develop a successful polypharmacy course of treatment for a given patient, but it's a bumpy process that often takes years of experimentation and evaluation.
But getting back to the thing you (the OP) actually care about, ask your doctor about switching to Effexor (venlafaxine) instead of cymbalta. If s/he chose Cymbalta because it has some efficacy against chronic pain and neuropathy, ask about accomplishing that with perhaps gabapentin instead, so that you'd be swapping out Cymbalta for Effexor and gabapentin.
As for the Abilify, I urge you to stop that (ask your doctor first, of course...), especially if you are young-ish, i.e., if you expect to live more than another 5-10 years. My understanding, informed by three expert doctors, is that for someone taking abilify, the question is not *if* they'll develop tardive dyskinesia, but rather *when* they'll develop it. And TD is largely irreversible, I think. At a minimum, you should seek a second opinion. Also, I don't know your insurance or financial situation, and I'm not sure whether it's still on-patent, but back when I briefly took it, only the brand-name was available, and the cash price was like $700/month. I had pretty decent insurance, but I still had a $60 copay each month.
But I digress... Best of luck and G*d bless!