Mine is set up in accordance with the German STVZ0 requirements which say that the centre of the beam should drop to half height at a distance of 5 metres. (about 2/3 rds the way down the following link) Pretty sure there was a recent thread about this. No problem that I know of to any motorist and enough penetration for 25-30 mph in pitch black lanes descents. Looking at the light in situ, the glass is vertical or very slightly tilted up.
https://swhs.home.xs4all.nl/fiets/tests/verlichting_analyse/verkeersregels/de_stvzo/index_en.html
The author of that article actually disagees with StVZO's requirement for aiming the light! At least that's how I read, as it's a very long winded article.
I do think StVZO's requirement aims too high and does result in dazzling. It's like a car's full/high beam pointing almost straight ahead.
This is where lit and unlit roads need different aiming. For lit roads, I want the beam to light up the road surface ahead of to reveal pot holes, glass etc. I don't need to light the side edges of the road, junctions etc. Therefore I aim my light so the cut off (top of the beam) is several metres ahead, ie all of the beam falls onto the road surface, and I can see the cut off on the road surface. For faster speeds, the aim is a bit further at the cost of reduced brightness, if I'm going slower then I can point it down more with increased brightness.
On unlit roads, you do need to aim higher to see where you are going and also just in case a deer suddenly appears in front of you. If you are lighting up what's in front of you and not the road surface then it's going to dazzle.
I've only used StVZO battery lights, on my bars, and set the bracket just tight enough so that I can aim the light up and down.
Also I would think the height of the light makes a difference.