While not necessarily being an expert, I have extensive experience in biomedical scholarly publishing as author (>500 scholarly papers published) and reviewer (>1000 manuscripts reviewed).
Most of my manuscripts have been rejected several times before eventually getting accepted and published, as this is quite typical of cardiovascular research. Indeed, I mostly dedicate myself to incremental research, such as meta-analyses and observational clinical studies, and often submit first to a top tier journal (e.g. with impact factor above 10), then trying to lower impact journals.
I now tend to favor not changing substantially my manuscripts after a rejection, even if accompanied by peer reviewers comments, as I feel that in most cases this has to do with a priority judgement rather than with the work strengths and weaknesses. Of course, I address major mistakes or issues, but I typically avoid adding ancillary but time consuming analyses in such cases.
Is this acceptable and efficient, or actually unethical and disrespectful of the peer review process?