Think of resistivity as the 'crowdedness' of a hallway; the material's internal structure determines how difficult it is for a person (an electron) to walk through without bumping into walls or other people, irrespective of whether the hallway is short or long.

The resistivity is governed by the microscopic parameters of the material, specifically the relaxation time ($\tau$) and the density of free electrons ($n$). The relation is defined as $\rho = \frac{m}{ne^2\tau}$, where $m$ is the electron mass and $e$ is the electron charge. Since $n$ and $\tau$ are determined by the electronic structure and lattice arrangement of the specific element or alloy, resistivity remains constant regardless of the sample's shape or size.

Always distinguish between Resistance (an extrinsic property that changes with shape) and Resistivity (an intrinsic property that is a constant for a given material at a specific temperature).