My interest in debouncing comes from personal experience.

I work on an application that has a precise requirement for debouncing 13 inputs. Simple (and cheap) RC low-pass filters ensure that the CPU does not see changes of less than 10ms and the software debouncing ensures that all changes of less than 200ms are rejected and all changes of greater than 250ms are registered.

I have previously iterated through the inputs using one counter for each – this method works very well, but is processor intensive. The method of vertical counters or LFSRs, will be much more efficient.