General Coat Patterns Questions

I tend toward leaning following the guidebook outlines (with ref to dog-gene markings like brindle, merle) but some markings- such as having ticked guard hairs, some darker fur or lighter fur around the shoulders, different coloured tail tip, darker ears, vitiligo, etc. Those are more naturally occurring in nature. Heart shaped patches also occur in nature, but other patches and stuff tend to be rarer. 

If I'm not sure, I just go on a good ol' google search to see if I can find a pattern and colour combo that is found in nature and go by that :)