in my case I'm constantly double and triple checking they won't do something stupid
And after the triple check? What if they do that 'something stupid' you've intelligently been looking out for?
I know I'm kinda risking labouring this to the point of being a pain in the are but I am intrigued. What would you do? Would you stop? That is, stop mid roundabout, with maybe a vehicle behind you?
My point is, assessment is one thing (a huge and important thing, a life saving thing) but one has to be prepared to act upon it, and know in advance what that action might be. The vast majority of times being aware is enough in and of itself, and as said above can alert the other vehicle user to your presence, but I think it can help to think further than that and consider 'what if' scenarios. What if they do 'something stupid'?
I have once stopped, approaching a junction with a road to my left. I was on my bicycle and I had right of way. A car arrived at the junction. It had dark (not just tinted but dark) windows all around. I could not see the driver, I had no idea what they were looking at. It was 6am-ish (light but early) and it was a rat run area. I may have had the right of way but
no way was I going to risk them not having seen me. I was not going to cross in front of them so I stopped and let them go... but there was nothing behind me and I could safely do that.
Conversely, when on the motorbike, I've not stopped at traffic lights as they turn. Not run them per se, they've turned amber and I could have stopped safely, but I've elected to go through. I've been aware that the car behind is just a little too close, perhaps wanting to get through the lights, and may not be so inclined to stop.