Is it advisable to have a color scheme within a color scheme?

So I have finally decided on a color palette to use throughout my my house. I am going to have brown/beige as the main color, black as a secondary, and white as an accent color. I plan to stick to the 60-30-10 color division, but my problem is this: it's hard to find things in an exact shade of brown. Some browns are more of a beige while others are deeper or orange-ier. So I'm thinking of doing a monochrome color scheme in browns- while pairing it with black as a secondary and white as the accent. Do you think this would look alright or will it be overkill?