Reaming a drilled Hole Prior to Tapping..?

[EmilioG]

I watched a video where the machinist reamed the holes then tapped them for better results.
Has anyone done this and is it worth doing? Does it make sense?

 

[JimDawson]

For really accurate holes and threads I ream before tapping. I only do this when the fit is critical or the thread depth is very shallow relative to the diameter, like a 1 inch - 32 thread (for CCTV lens mounts). For normal use it is not needed IMHO.