In order to achieve the best finish, and most accurately sized holes, the speed at which they are drilled needs to match the material used and the drill size and type.
The handheld cordless drills have variable speed controls on the trigger, and with experience one gets a feel for what works and what doesn't.
But these tools are mainly used for rough work. On he other hand, the bench drill and pillar drill can both be used for more precise work, and adjusting the drilling speed is more time-consuming. For this reason, they should both be left set at the speed most likely to give reasonable results for most applications. Where this speed is inappropriate, it should be adjusted before carrying out the work, and reset afterwards.
The following table gives an indication of speeds to use for various materials and drill sizes.