I'll have to admit, soaking blocks over night on ice does seem a little excessive.   I work in a veterinary lab so of course all we do is process and cut animal tissue.  I would say that on average we let our blocks soak and chill for about 10-15 minutes.  

Renee Escalona, BS, HTL(ASCP)
Diagnostic Laboratory Supervisor
Texas Veterinary Medical Diagnostic Lab
College Station, TX