Interesting that the leaflet on Electronic Conspicuity contains a blanket statement
Of course you can do simple things to
help yourself be seen such as switching
on a beacon or strobe lights (and why
not the nav and landing lights, it doesn’t
cost any more money)
It's worth noting that lighting needs to be something like an order of magnitude brighter than the background to make you stand out. In the worst case turning the landing lights on may make you blend into the background as you'll be around the same brightness rather than a contrasting black dot. That's not to say never switch them on, but if it's a summer's day and the sun's behind you they may be better off.