Each color plays their part. Less is more. Each element is made to do more.
When working from life you take a fragment of the world then attempt to make it whole by making sense of the loose ends left when it was torn from the world. If you can not find the right color find an equivalent. Colors that have a similar relationship.
When painting from life before you use any color for a particular object compare it to any similar object. Ask which is more or less intense, lighter or darker, etc. Reserve the most intense or darkest to where it is really needed.
There is sometimes a place for out of the tube colors. At other times they are a bit like a naked person on stage. One sometimes needs to dress properly to fit in. (to the larger picture.) Sometimes the one object or color that attracts is the one thing that distracts from the whole. In this case a support needs to be found to anchor the color to the whole.