I have a triple, my big ring is a 52, and I use it:

down hills

when there's a tailwind

when I'm drafting off someone or in a pack and the speed is above 30kph

Also when in a pack I find that I feel more stable and in control when pedalling at a lower cadence (70 to 80), which still feels easy (no need to put weight on the pedals) so this often means going in the big ring because of the speeds we're going at.

When I'm riding on my own, I nearly never use the big ring, unless as I said I'm going down a hill or there's a serious tailwind.

If I need to accelerate (catch up with a pack or something) I'll most of the time actually downshift to an easier gear and increase my cadence a lot. Pushing big gears slow me down.