Many of these folks have comorbid personality disorders (not suggesting your patient does).
Don't try to interpret someone's history by their Rx list.
I have several patients with dependent personality d/o's and cormorbid depression and anxiety/panic d/o.
I've done this on a number of occasions with antidepressants and other categories of meds as well.
These folks often are the ones that end up on some dangerous med combos, typically involving our friend Xanax.
Rather than add on more drugs, sometimes it just more effective (and safer) if you say something like, "Well maybe we'd get better daytime coverage of those symptoms if we split the dose in half..."
If it does no harm, then there oughtn't be any harm in trying it. If they respond well to the change, then so what? Leave well enough alone. If I inherit a patient from a doctor who's retiring and they're on Prozac 10mg TID and stable/euthymic, guess what? I'm refilling that Rx exactly the same. The dumbest thing I could do is try to explain why it doesn't make sense pharmacologically (not to mention waste my time).
Placebo isn't a psychological phenomena, it's one of our tools. Yeah, I get it though. From a pharmacological perspective it makes no sense, but we're not practicing psychopharmacology, we're practicing psychiatry and boy does it may your life easier when you follow up with someone who's on Prozac 10mg tid and they're telling you it's the perfect regimen for them. Your real struggle with doing things like this is overcoming your own ego for fear of ridicule/embarrassment by another colleague who understands the medication and not having the opportunity to justify or explain your medical decision making. But don't let that stop you. You're the brilliant psychiatrist who has kept their patient euthymic, stable, functional, and off of those other nasty meds.
Rx: Prozac 10 mg TID, #90, 3RF