I've always been of the opinion that the primary objective of a landing light is to enhance visibility of my aircraft to anybody or anything ahead of me - most likely on the runway.
Hence I use it during approach and landing, and also flight in poor visibility, especially at lower levels (say 1500ft or below) where it might provide a small edge in conspicuity.
I don't normally use it on take-off, but reading some of the posts here, I can see why that is a legitimate use, and maybe I should.
As they can be a little fragile, and frankly it's just wasting a tiny bit of fuel, no I don't use it all the time as a conspicuity aid - that's what strobes are for.
G