I have been adding 7 drops to my lather bowl and dripping lather from my shaving brush/mug on top of it before bowl lathering. The benefits gained for me are evident while using my straight razors. I get better glide (no sticking or chatter) and the lather does not dry out on my face as quickly. These attributes are important while using a straight where I shave more slowly than while using a DE and the glycerine helps me avoid cuts from the razor catching on my face. Glycerine is not so important while DE shaving, but it does not harm the shave quality in any way.