One thing about "high" speed descents is they are less economical from a fuel point of view! Some pilots are under the misconception that staying high in the cruise for longer and then descending high speed will save fuel - this is not the case! It may reduce tech log time so there is an issue with maintenance costs etc but this is the idea of having a cost index on the fmc which will give you the "ECON" speeds which balance fuel burn against time in the air.
Hope this helps - fly safe!