Need to normalize lattice enthalpy by no. of nearest-neighbor (NN) interactions to equate to NN interaction strength?

I've seen electrostatic interaction energy (from $E\sim \frac{q\_1 q\_2}{r}$) used to explain differences in lattice enthalpies between different crystalline solids. For example, I've seen it explained that $\ce{NaF}$'s $\pu{910 kJ/mol}$ lattice enthalpy is less than $\ce{MgCl2}$'s $\pu{2326 kJ/mol}$ because of $\ce{Mg}$'s greater cationic charge (+2 vs. +1). 


Question: Isn't the lattice enthalpy defined per stochiometric unit, rather than per nearest-neighbor interaction? And if so, if one is going to use electrostatic models of nearest-neighbor interaction to explain differences in lattice enthalpy, shouldn't the respective lattice enthalpies first be divided by the number of nearest-neighbor interactions per stochiometric unit? 


