When applying this under my eyes, I did two dabs under each one, as tiny as I could make with the applicator. I then made little circular and back-and-forth motions to blend it in (like in the video here). The denseness of this brush and the bristles' angle did in fact make it very easy to use under my eyes.
This Hourglass concealer seamlessly blends in but sets very fast, so instead of doing my normal dots under both eyes at the same time, I did one eye at a time. On my dark spots, I also added a tiny dot, but I did more of a dabbing motion there instead since I was focusing on a smaller area. I didn't notice any visible streaks or lines from the bristles either time.
Image Source: POPSUGAR Photography / Morgan Ashley Parker