The last pours set the strength.
The remaining 60% controls body: more, smaller pours extract more and taste stronger; fewer pours taste lighter.
What it is
In the 4:6 method, the last 60% of the water decides how strong the cup is.
Why it matters
Splitting that water into more, smaller pours extracts more and gives a stronger cup; fewer pours give a lighter one.
In practice
Three pours is the usual start. Try two for a lighter cup or four for a heavier one, keeping the same total water.