The biggest pitfall of a tetradic scheme is visual chaos. If you use all four colours in equal amounts (25% each), the design will look messy, busy, and unbalanced. There is simply too much competition for the viewer's attention.
Use the third color for highlights or call-to-action buttons. tetradic colours
A (also known as a double complementary scheme) is one of the most complex and richest colour harmonies available in colour theory. It involves the use of four colours that are arranged into two complementary pairs. The biggest pitfall of a tetradic scheme is visual chaos