A variable strength proppant pack may be useful in maintaining a higher porosity and conductivity of the proppant pack over time. Forming a variable strength proppant pack may involve introducing a fluid having a composition into a subterranean formation having a fracture network therein, wherein the fluid composition changes between a plurality of compositions that comprise: a first proppant-laden fluid comprising first proppant particles, and a second proppant-laden fluid comprising second proppant particles having a crush strength greater than a crush strength of the first proppant particles; and forming a proppant pack in at least a portion of the fracture network, the proppant pack having first proppant portions comprising the first proppant particles and second proppant portions comprising the second proppant particles.