It is best practice to switch off "Tangent Space Normals" in Foilage material?

I’m trying to trouble shoot my grass lighting. The normals are all pointed upwards but each plane thinks the sun is coming from different sides, hence some planes have SSS on the one side whilst another plane has SSS on the opposite side. It’s set to Two-Sided foilage.

When I switch off “Tangent space normals”, the grass starts to shade correctly, although I’m not sure if its correct to plug a tangent space normal and still switch it off in the materials…any suggestions?