At a fundamental level usability is decomposition of a big activity with all the required know what and know-how for a desired outcome in simple chunks, in a way that makes sense as a whole
Very similar to how a good film editor would work, whenever they decide to cut they are at the same time thinking of how each scene cut fits into overall plot and character development
You break a complex activity into parts but you preserve the felt sense of the whole for the intended outcome of each feature's usage, aka building a lasting mental model
Anyone can slice. Very few can slice without destroying coherence.
A bad editor cuts scenes mechanically.
A great editor is always holding three timelines simultaneously:
What is happening now
What the viewer already knows
What emotional / narrative state we are building toward
Designers who grok usability operate identically.
When you design a flow, you are silently managing:
cognitive load
emotional state
uncertainty
momentum
trust
narrative continuity
You are editing human experience. Not screens.
If decomposition is done poorly, the user feels:
fragmented
lost
unsure where they are
unsure what they just did
unsure what comes next
This is why many “clean” apps still feel terrible.
They are locally simple.
But globally confusing.
The real skill is: finding the natural joints of an activity.
Great designers cut at the natural joints of human intention.
Not at database boundaries.
Not at engineering modules.
Not at org charts.
Not at feature lists.
But at places where the human mind naturally says: “Yes… this is the next thing.”
When that happens, the interface facilitates a memorable flow for an activity
Raghav Agrawal