This is not a TA principal, just an observation ...
These sideways movements, seem to have the effect of resetting momentum indicators. I mean to say that momentum indicators call the bottom, but then price moves in this sideways fashion and causing the momentum indicators to shift upwards - as if an impulse wave were taking place.
Stated in simple terms, we are in the Bermuda Triangle and the compass just spins in a circle. All we have to go on is the study of similar, previous price iterations and the EW rules of complex corrective patterns.