This 2020 article in Psychiatric Times says:
An international consensus study recommended that antipsychotic dosing in acute schizophrenia should aim for 2-fold to 3-fold MED (Minimum Effective Dose)
This 2020 article in The American Journal of Psychiatry concludes:
In chronic schizophrenia patients with acute exacerbations, doses higher than the identified 95% effective doses may on average not provide more efficacy. For some drugs, higher than currently licensed doses might be tested in further trials, because their dose-response curves did not plateau.
Shows dose/efficacy charts for common APs.