I use only sidelights sometimes, if I want to be more visible from the erm, rear……my car is fairly dark grey and so there are times when I want people to have early warning I am there. Drivers coming towards me don’t perhaps require the same level of ‘me’ visibility as they are normally in their own lane.
Generally I just stick the headlights on and be done with it though….
And nothing annoys me more than ****ts who drive with fogs on when it is not necessary – particularly as someone said up the page, when it’s proper dark, but they think sidelights and fogs are acceptable.