Many years ago you could have either a big capacitance in a high inductive package or a small capacitance in a low inductive package. So, paralleling of both was essential to achieve a low impedance over a wide band of frequencies. Unfortunately this paralleling often resulted in resonances, where the inductance of the one cap reacts with the capacitance of the other. Consequence: Impedance maxima of dozens of Ohm where you want to have an impedance of much less than 1Ohm.

As long as you use a cap for the bigger one, which shows enough equivalent series resistance, these resonances can be kept small. This is why putting a small tantal or simple aluminium electrolytic in parallel to the 10...100nF SMDs is so helpful.

Today, situation is totally different: Ceramic high caps are available, which offer huge capacitances in tiny SMD packages. So, it's easy to get a 10µF cap (X5S) in a 0805 package.
When using such caps this annoying paralleling is no longer needed!

You can drastically enhance the filtering performance when using ferrite beads in combination with these caps. By using a simple pi-filter configuration you can suppress the resulting ground return currents to nearly zero, which allows you to combine analog and digital circuitry arround the same chip.

Kai