By putting all your money on one color, you just lost it all.
Instead, if you identify a major turning point in the scene where your character reacts to something just said or has a realization, and this causes a major shift in your character, perhaps he goes from angry to kind, you've just increased your chances of hitting the color they want.
You've doubled your chances.
If the director is in the room, she might direct you to that color. Or if the casting director knows exactly what the director wants, he might direct you to the right color. But the casting director isn't always sure what they want. Or the producers may change their mind after they've told the casting director what they want.
But when you go on tape, you often get just one chance. Why not increase your odds by showing them you can do more than one emotion, color, or level?
How do you do this realistically, organically, and naturally? Find at least one moment of transition where you shift to another color or level because of what the other character says or because you've just realized something. Even if they hate the way you do the first half of the scene, if they see what they need in the second half of the scene, at least they know you can do it and they can easily get that out of you on the set. I encourage actors to find such a moment about halfway through the scene. It usually occurs after the other character has said a line. And it often occurs where the writer has indicated some kind of action in the script. (For example, "STAN stares at BLANCHE, then turns away.") And you can take your time with the transition moment where your only job is going from color 1 to color 2.
Most audition scenes need only one major transition point. Even the shortest scenes could use one. The exception would be a scene with only one line, but even there you can start the scene with one intention and as a result of the cue line, shift to another intention. Don't go crazy and try putting transitions everywhere. More isn't always better!
If you find transitions in your audition scenes, your work will be more interesting. It'll be more surprising and unpredictable, which is what good acting is.