It depends on the context. As an intermediate step I definitely write things like x (3) meaning multiplication, as it can more clearly indicate what's just happened (see my other comment in this thread).

There's other context too, based on what is known. Up to a certain point in first year at my university, most engineering students haven't ever seen functions named x and y, and so they'd mostly interpret x(3) as multiplication. Then we show them parametric curves, and suddenly x(3) looks like the x coordinate of a point on the (x(t), y(t)) curve.