Ceiling becomes too stiff if you use too many clips up front. You only add clips as you increase the load. What we're really trying to do is lower the natural resonance frequency of the wall or ceiling. Adding mass, be it drywall or wood coffer, all helps the cause a lot.
Once a system is effectively decoupled, we use the variables of mass, cavity depth, and absorption (yes/no) to drop that resonance frequency as low as we can. Interestingly, damping does not help change the frequency of this resonance, it simply reduces the severity of that resonance.
The Soundproofing Company