Charging the puddle with different pigments can create  beautiful, subtle changes in color that result in an illusion of three dimensional form, light striking an abject, rich shadows ... seamlessly.  with practice, you'll know how much of the new pigment to add and when to add it.  You will then watch the watercolor perform its natural magic.  I'm posting several paintings as examples of charging puddles with different pigments.  Some of the examples are more subtle than others. I really encourage you to master this technique.  It has served me better than any other watercolor technique I know.  Have fun!  Be playful!  Let the watercolor do what it loves to do.

Notice how three-dimensional the butternut squash appears against the perfectly flat, blue background.  The entire painting was done with the Pulling the Puddle technique.

The fish scales are an example of charging the puddle with the complement of the original color of the puddle.

Notice how using color changes in the puddles of only some of the leaves still creates a beautiful effect of light and three-dimensions.

Holding to a close analogous color scheme when altering pigments in your puddles is also beautifully effective.

Snail Shells - a challenging subject made fun when charging the puddles with two, three and sometimes four different pigments!

Be bold!  Be daring!  You will reap the benefits and the joy of creating gorgeous paintings.