One problem with aiming for 100% perfection is that it tends to make you mechanical and rigid when you swim - so you lose touch with the rhythm of the stroke. It also means you try and over-ride rather than work-with your natural stroke mannerisms, which is extremely hard (or impossible) to do. A third problem with targeting 100% is you tend to overdo and exaggerate stroke corrections too much.
80% perfection might be a much better target - relax when you swim, lightly feel your movements and get it 'nearly right'. The Swinger knows the power of this more natural approach to stroke correction - it's the secret of their success.