Verry kool.
I generally chalk up extraordinary as rocket science. You get the see the market MOVE. Force in action.
Then you see earliest small stuff that leads to stalls, hitches and finally dips and as you say a traverse ending event.
The unsustainable is DU and VDU land. The traditional term for it is "four o'clock" drift referring to the hour hand. This is also where the corrollary to the P, V relation comes in. It is "If volume is steady and unchanging, then the price will drift downward." Here, you can see that the most frequent occurances of steady volume do occur when volume is very low. Noise comes into the picture also. As random as noise sounds, there is still human nature to content with. Active traders are not active in the trading sense at these times; but they are there and thinking and planning and looking for what sailors call telltails. The pieces of yarn you thread your main with to assure minimum turbulant flow anywhere.
So what happens? Not much and the risk is the highest that abounds. It is a tick talk time.