  Disentangling the effect of initial conditions and medium properties is an
open question in the field of relativistic heavy ion collisions. We argue that,
while one can study the impact of initial inhomogeneities by varying their
size, it is important to maintain the global properties fixed. We present a
method to do this. We show that many observables are insensitive to the the hot
spot sizes, including integrated vn, scaled distributions of vn, symmetric
cumulants, eventplane correlations, and differential vn(pT ). We find however
that the factorization breaking ratio rn and sub-leading component in a
Principal Component Analysis are more sensitive to the initial granularity and
can be used to probe short-scale features of the initial density.
