I think there is no better example for the effectiveness of BD...

I think there is no better example for the effectiveness of BD (assuming you know how to use it) than on AVZ

AKM
RCL
TNO
GAL

current examples where good BD has proven to be accurate

I can give countless other examples

Having used it for many years it isn't something that is black and white

You need to study it pretty intensively for a long period to get the feel for it.

It is not the holy grail but if used with solid TA it certainly increases the probability of a trade being successful.

Also it is T + 2 and chi-x does not account for 50-60% of volume in the vast majority of cases.