Raghu:
Using 100 msec as the sample interval for switch debouncing may be applicable in some cases. In other cases it may not simply becasue the 0.1 to 0.2 second delay from the user button press to the action it is supposed to cause can make a user interface on a product seem very sluggish. It can also be an issue in a key detect handler if it is designed to report key repeats. If you are designing this way and using an "arrow" key to adjust a parameter that has many steps the 0.1 second repeat rate could end up taking 25 seconds to go end to end on the parameter adjust.

Just some thoughts.
Michael Karas