You are partly correct, large amounts of water do move through the pore spaces in rock. However, in addition to that type of flow, almost all rock formations have a network of cracks and fractures, and water often moves preferentially along these pathways. How much porous flow vs fracture flow you get in an aquifer depends on the nature of the rock and the degree of fracturing in the aquifer. In wells, intersecting a few good fractures can be the difference between a productive well and one that does not produce sufficient flow to be useful.