CDCE913-Q1: Layout Guideline for crystal

Part Number: CDCE913-Q1

Tool/software:

In 13.1 Layout Guidelines, you recommend to cut out both ground plane and power plane under the area where the crystal and the routing to the device are placed. Do we need to cut several layers or just the adjacent layer?

And we've see many other products ask us to keep a solid GND plane directly under the crystal-associated components and trace instead of cut it out.

What's the advantages and disadvantages of these two methods?