Total number of colors in a room without it looking too “busy”?

Not sure what you are asking. I have done 3 walls in one color, 1 wall with wallpaper and a white or different color ceiling. Looked great!

Start with three, such as fawn, brown, and light, light, peach.

The average is three colors.

3 is the textbook answer, but I believe in doing what makes you happy when you look at something. I love pink, and I notice that when I see it anywhere, I automatically smile. Do what makes YOU SMILE.

3 colors. One should be more neutral like gray or tan. One should be used in smaller doses for a punch of color. A pattern on drape, chair / pillow / area rug / painting should help pull them all together.

I agree... three is optimal... but don't discount something you love for the sake of three!

I say 3 a small room and 5 for a larger one