I was suspicios of the whole waste thing from the beginning. "Waste" is such an abstract concept that it does not apply to any real situations that would affect all living things. There are reasons for some things to be "not possible to utilize" or "harmful to keep", but they cannot be generalized.
Same with fatigue - its effects differ for different organisms and different actions.
I would say that we already have fatigue. If I remember corrctly the stack can overflow and not accept any values if genes place values in it and don't remove. So if a movemement gene places more values on stack than it removes (and if other genes don't remove these values fast enough), then in several cycles the stack will overflow and movement gene will stop working.
Of course, this is not a problem with man-designed bots, because designer can always remove those extra values, but for evolved bots this scenario is quite likely.