Statistical clock tree design

Clock skew is a function of process variation, i.e., delay from the clock source to a leave of the clock tree is a statistical function. A rule of thumb for minimum process variation clock tree design is to have balanced branches, i.e., identical buffers from identical distances to the clock source, and symmetric clock routing branches with identical capacitive loads. Can you have a more flexible clock tree design scheme, while maintaining a minimized/bounded clock skew from a statistical point of view?