For the double excitations we systematically investigated the tradeoff between speed and guaranteeing occupied or empty orbitals in PCHB and determined which combination of uniform or (constrained) weighted PCHB sampling is the fastest, to date not present in the literature. In this work we show that the choice matters, considerably improves the excitation generation of doubles, and depends on the system at hand. We also improve upon the current literature by examining how to efficiently draw from constrained distributions, for example p(I)| I∈|D i from the precomputed p(I).