Perhaps if he feels too safe, he can't give as convincing a performance. And now for a little commentary on technical perfection. In the twentieth century, performers have attained what seems to be a higher level of technical perfection than was attained during past ages. Performances are then alienated from the effort of music-making. I recently went to a double bass recital where one piece required the bassist to play harmonics below the fingerboard.
Most performers practice with a metronome ticking, especially with more difficult music.
As we discussed this week, metronomes didn't exist for most of the baroque and classical periods, and when they did, no one used them to practice steady time. So when we use them to make the beat absolutely steady, we are losing expression and control over the music. We artificially play everything completely evenly and then must go back, when the metronome is off, and add freeness to the performance. And often what we would add to the strictness is hardly perceptible. I've frequently heard some of Bach's most tragic preludes from the Well-tempered clavier played absolutely in rhythm.