When I had my light mounted on my handlebars, I covered it most of the time. I have since attached my headlight to a small front platform rack. While I can (carefully) reach far enough to adjust the angle of the light or get to the on/off button. That said, my light is aimed down and I’m using a lens filter to disperse the light horizontally so I hit a wider swatch of the ground in front of me. I see people cover their lights and sometimes wish I could reach down and cover mine, if for no other reason to let them know I understand and appreciate their gesture. I’ve even entertained the notion of putting my headlight back on my handlebars, especially since my mounting hardware for the light on the rack set me back all of $5. OTOH, the aim of my light and the lens mean it’s not blinding to oncoming riders, and I tend to run it on the medium setting most of the time.
Can’t wait until I eventually replace my lights with dynamo powered ones w/ sharp vertical cutoffs so I can be even more sure I’m not bothering others.