You have to understand the context...
Leung Ting teaches 7 sections of Chi Sao (basically choreographies of movements from SNT and CK), followed by four sections consisting of moves from the third form, etc.
But this is all chi sao, and as Leung Ting puts it himself, all the cs skill in the world does no good if you can't contact the opponent's bridge.
So after the 7th section he teaches 5 five "attacking methods" (Lat Sau) to teach the student to move in on the opponent and attack the opponent while bridging.
In the EWTO we didn't learn like that, but for the 9th student grade (that means after completing the first section CS) we learned 12 so called attacking methods, some were the same as in Leung Ting's five, others were not.
Anyhow, it is very basic stuff which I am.sure any other Wing Chun lineage teaches as well.