Superposition on a circuit with just one source
Superposition is actually used. 

For a start assume V3 and V4 are zero then 

V2 = -V1*R4/R1

Then assume V1 and V4 are zero then

V2 = \$\dfrac{V3\cdot R2}{R2+R3}\cdot (1+\dfrac{R4}{R1||R5})\$

Then assume V1 and V3 are zero and solve V2 in terms of V4

Finally, add all the different versions of V2 together as per superposition