That's an important point, on a typical ERP installation, my observation is there are very few Gateway / UI5 applications you can use as a reference for formulating a best practice. If there are bad practices, loose standards and inconsistencies these will likely be copied by the developers on customers sites (like me).
Interestingly i was told that there are very tight UX metrics around the performance of the Gateway services used by Fiori apps, and some apps have not made the grade and therefore were not accepted, would be nice if these metrics were shared.
JSP