Comment by yomritoyj

ML practice has for the moment far outstripped ML theory. But even if ML theory catches up, the answers to your question will get likely be still dependent on the nature of the process generating the data and hence they would still have to be answered empirically. I see the value of theory more in providing a general conceptual framework. Just as the asymptotic theory of algorithms today cannot tell you which algorithm to use, but gives you some broad guidance.