The answer to that depends very much on whether the programs in question use IO of some form.

If they do, then one program can be utilising the processor whilst others are waiting for IO to complete.

The time between clicking the link in your browser and the page starting to render on your screen. 2 to 10 seconds depending, is cpu dead-time that can be utilised by other programs. It's the extreme example, but even the delay on reading from a file--moving the head to the right track and then waiting for the disk to rotate into the right place--is often several hundreds or thousands of clock cycles that can be utilised by other processes. Caching complicates things of course.