The discussion is not about whether edges exist or not. That is off-topic, discussed many times in other threads and should belong to the class of "does TA work?" type of questions... I define edge as something better than random, objective and quantifiable. If you don't believe in such things, fine, you have such right. But please, don't ruin the thread..
Yes I believe and agree with your above question. For example, and just to expand a bit, an edge developed in a given volatility, i.e. VIX, will not necessarily perform well in different VIX environment. I think therefore it's important when one develops an edge they take notes on VIX because as we have all seen VIX changed a lot of the last 6 months 12-20, back to 16 and back over 20.