Can multiple Schmitt triggers in series fully debounce a switch?
Can multiple Schmitt triggers in series fully debounce a switch?

A single Schmitt trigger with a analog filter in front of it can be used for debouncing.  However, after that Schmitt trigger, the signal is fully digital.  Any additional Schmitt triggers won't change that.  Ideally they will preserve the signal.

On a separate topic, debouncing in firmware shouldn't present much of a load.  The usual way is to sample the switch state in a periodic interrupt you already have anyway.  You declare the debounced state the current switch value when you've seen the switch in that state for N consecutive samples.  I usually require the switch to be in the same state for 50 consecutive 1 ms interrupts for the new state to be considered valid.  That usually takes a very small fraction of the overall processor cycles.