Just because evolution of certain details can happen on short timescales does not therefore mean that evolution can or does make any old change in a short timef

Just because evolution of certain details can happen on short timescales does not therefore mean that evolution can or does make any old change in a short timeframe. Evolution tends to operate as a hill-climbing strategy (not to say it cant clear away exising design details) so it often produce (non-fatal) 'bugs' in its designs that never get fixed.