It's a debatable issue that RCTs are conducted in very controlled environment, whereas, in clinical settings, the scenerio is quite different. Further, it's not suitable research design for all systems of medicine. Therefore, is it correct to say RCTs as gold standard evidence or we have to explore more N of 1 type of designs.
Excellent question here! You are correct in your observation that RCTs are not always suitable; that is to say, an RCT is highly controlled and only answers a very specific question in a very specific population of patients. Thus, RCTs are often not applicable to a large segment of the patient population for which that study is targeted to. It becomes increasingly important for physicians and researchers to parse out these specifics so as not to improperly interpret RCT results and erroneously assume that they apply to a wider patient population than reality.
However, the advantage of this study design is that for patients who fall into that specific study population, we can be fairly certain the results provide meaningful information that can guide clinical care (assuming proper power, statistical analysis, etc). In an ideal world, there would be RCTs that guide the management of every disease in every type of patient, though the best we can do now is make inferences based on our clinical experience and acumen.
I would treat this an issue of internal versus external validity. If you are trying to rule out other factors that may have produced an experimental result (i.e., internal validity), then RCTs have very notable strengths. On the other hand, if you want to determine whether the results from experiment can apply to other settings (i.e., external validity), then RCTs have equally notable weaknesses.
In addition, I have recommend the concept of "transferability" which is more commonly considered in qualitative research. In that case, you have to consider the extent to which any set of research results can be applied in some other setting. The more the two settings differ, the less like it is that the results will be transferable.
Shobit - this is more a case of a popular misconception. This common 'myth' works on the basis that all RCTs are high quality and rigorous - and that is definitely not the case. Medical hierarchies of evidence are often criticised as too 'simplistic' i.e. RCTs (Gold Standard) and qualitative/ mixed methods research does not even feature in the hierarchies as evidence. You can have excellent qualitative findings and poor RCTs. Which one is best to align to practice? Of course, no single study outcome should determine practice - so let's take systematic reviews of clinical trials i.e. Cochrane. They are viewed as the very pinnacle of medical evidence - yet, again, flawed. Cochrane favours positive reviews - and not negative outcomes. For every positive systeamtic review - there are many unpublished negative reviews - so we get a very skewed picture of medical evidence.
Ben Goldacre does a series of excellent TED videos on the matter. Well worth a watch.
https://www.ted.com/talks/ben_goldacre_what_doctors_don_t_know_about_the_drugs_they_prescribe?language=en
https://www.ted.com/talks/ben_goldacre_battling_bad_science?language=en