I think we can all agree on the part in bold about doing SOME workout that give you confidence and mental strength. If we can strip down the two purposes of training, the first is to make the body physiologically stronger, then once that is done, then it's about using the mind to optimally extract as much race day speed as possible out of the maximally optimized physiological state. The question really is about what needs to be done to get to that physiological state while also getting to the mentally optimized state. In the quest for the latter, you don't want to give away any of the former.
With respect to nothing really ever been proven, if anyone agrees with that, it would be me....however after a long period, we find that certain hypothesis end up solidifying with a large number of data driven observations from which we can draw some solid conclusions...in that vein, as Dan Empfield has said, we are all more alike than we are different and the N=1000000 results like apply equally well to your N=1 sample size, in other words, while you may be an outlier in some areas (the top line numbers of our engine), you're likely not an outlier when it comes to how basic human physiology is maximized. So do you really want to waste potential performance upside by experimenting on yourself, or do you want to get the most out of you.
If you want to maximize the mental game, go spend some time with Macca (well when he as on), Whitfield or Peter Reid. These guys are masters of this. No need to experiment much. Anyway, consider another path. You might be unbeatable if you do.