Back bevel on planer knives

I had been watching "wood works" with David Marks on DIY when it was still on He mentioned during a shop tour show he had a back bevel put on his planer and joiner knives to reduce tear-out. I would like to know for one does this help with tear-out in figured woods and what is the angle I should try to put on the back bevel?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.