The CATIE looked at several different dosing strategies for antipsychotics and most concluded that once a day was better tolerated, had lower doses, and were re-hospitalized less for schizophrenia. The one I see most commonly used BID where once daily is the same and tends to be at lower doses when hitting max efficacy is risperidone.
this study tries to argue for divided dosing for clozapine but isn't a clinical trial:
Clozapine, generally considered to be the most effective antipsychotic, is the gold standard for treatment-resistant schizophrenia. With a relatively short half-life of 12h and a very quick dissociation rate from the dopamine D2 receptor, pharmacokinetic and pharmacodynamics principles would...
pubmed.ncbi.nlm.nih.gov
The product monographs recommends that clozapine be administered more than once daily if the dose exceeds 200 mg/day in Canada.
Whereas this cross-sectional study looked at patterns of once vs twice daily dosing:
Despite the product monograph recommendation, clozapine is frequently prescribed once daily in North America. Further studies are needed to compare clinical outcomes between once-daily vs. divided clozapine dosing.
pubmed.ncbi.nlm.nih.gov
There's one clinical trial that was trying to look at this in a double-blind RCT. Not sure what the status of that study is though.