There are two legs only because traders want to see it that way.
they see it, yes, because it is they, as a group, as a crowd, who created it.
if the first move is strong then traders expect further strength.
but what makes the first move strong, is the weak opposite move and renewal of the first strong leg, when it goes through the weak move.
this will continue until one move is weak and they will expect weak moves.
this goes on all day in all time frames.
you could measure it by observing the legs and that is what i do. that is what Brooks does and describes in his books.
you could do it in other ways ,i suppose but one way is enough for me.
i am not saying it is easy it took me long enough because it can get quite complex.... each two legs getting bigger or smaller.
it is obvious that those who say
'trade simply' are seeing some small pattern but not able to define it.
i used to do it for a long time and it is well documented here.
but it can really improve your trading if you define it and then trade it. the market then cannot use your own doubts against you and then you have the market by the balls