One of my favourite rides this past summer had about 8km touched up with about 2-4inches of fresh gravel the type you described and it became near impossible to ride enjoyably and safely. The rounded gravel is like ball bearings and its easy for your bike to get out of control on the downhills. The only good thing is that traffic will typically push the gravel off the road and into the ditch. Hoping by spring road conditions will have improved or that they touch up the road crushed gravel.