Hotkey brightness actually opens Display settings

This is by design. You first need to select if you are wanting to adjust the brightness during your activities, or for general use. If your screen has dimmed during your activity because it timed out, you may just need to select your LIGHT (upper left) button to brighten the screen.

But it means that the hotkey has wrong naming. It should be "display settings", not "brightness". 

I definitely understand your point. You will need to submit this change request on our 'Ideas' page.

Aside from pressing the top right button, there is no way to adjust the brightness of one singular screen or one 'moment'. You can only adjust and set your brightness level by first selecting either During Activities or General Use. This is why your Hot Key does not take you straight to the brightness level screen. If pressing the 'Light' button does not make the desired difference in your brightness, you may need to increase your brightness for your activities. If you want to save battery life, you can shorten your Time Out screen and still use the gesture motion or the light button to brighten your screen when it goes dim.

Garmin-Sierra said:

Aside from pressing the top right button, there is no way to adjust the brightness of one singular screen or one 'moment'

I have a 955 but I noticed a similar issue.

If I set a hotkey for Backlight, it takes me to the backlight settings menu (equivalent to hold UP > System > Backlight), which has a whole bunch of backlight-related settings.

On the other hand, if I use the controls menu (hold LIGHT) and select Backlight, I'm taken directly to a screen which lets me adjust the current backlight brightness (and nothing else).

Personally I would've expected the Backlight hotkey to have the same functionality as Controls > Backlight and not Settings > System > Backlight, since the former screen lets me change the current backlight brightness as opposed to general backlight settings.

What does Controls > Brightness do on 965? If it's like 955 and it takes you directly to a screen where you adjust the current brightness, I would expect the hotkey to do the same thing.

It's the same on 965.

Yeah I agree that this is unexpected behavior. A hotkey for backlight/brightness should let you change the current brightness in a single step, especially if there's already a way to do it in the controls menu (because that proves it's already possible). My expectation for hotkeys is they should give you access to the fastest, most context-sensitive way to do a given task.