Hi @haaris441,
Hope you are well! 
It depends on what settings you use under the Manage Tab >> Settings >> Materials >> (Opens Material Browser) Then under >> Graphics >> Shading options. (Check the shading override colors)...
Below is a few samples to illustrate the differences:
Wall without Shading Options or Surface Pattern, with the Visual Style set to Shaded:

Wall without Shading Options, but with Surface Pattern, with the Visual Style set to Shaded:

Wall without Shading Options, but with Surface Pattern, with the Visual Style set to Realistic:

They can be useful, especially the surface pattern for me and the visual style set to hidden when working with construction drawing to better illustrate finishes etc... But, it all depends on what your end goal is. Play around with it a bit in your project.
P.S. - Just opened a random project in our office...
I hope this helps! 
Rudi Roux
MSc | Digital Engineering Manager
LinkedIn
Revit Mechanical & Electrical Systems 2018 Certified Professional | Revit MEP & Architecture 2015 Certified Professional
AutoCAD 2015 Certified Professional | Autodesk Building Performance Analysis (BPA) Certificate
If this post resolved your issue, kindly Accept as the Solution below. Kudos are always welcome ⇘