Red Light Playing is a term musicians use to describe 'perfect playing'. The term is derived from when they are in a recording studio and the microphone is on. The red light is shown so that everyone knows not to disturb.
Whenever you are practising it is important not to just play through things and lose sight of mistakes, however small they are, either uncorrected or worse unnoticed. It is useful to compare yourself to the 'ideal' sound you are trying to create. This will challenge you to address the technical issues you and every trumpeter experiences. It is quite common for players to play over things that they can already play whilst 'sweeping under the carpet' bigger technical faults. However don't get too engrossed with being perfect especially if you start to find yourself practicing over and over one section. Always remember to improve you're trumpet playing rather than just working to death (which normally doesn't even improve that much) one passage that you're playing.
