When is technical analysis useful?

With respect to the efficient market hypothesis, when would technical analysis be useful to earn abnormal returns?

when the market is weak form inefficient

No, it never would. Weak-form efficiency says all past MARKET info (prices and volume, what Technical Analysis is based on) is already factored into the price. Semi-strong and strong both include market info as well, so TA is never useful (according to EMH).

Someone correct if wrong

oh sorry. INefficient. Yeah, mkipa is right

When nobody else is doing it, and there are lots of sheep in the market.

CFA’s stance on TA is that it never works. Some of the traders I work with use it a lot though.