Because it is a landscape you are trying to capture here, I would go for high level of detail, which you would expect with ISO 50. It is slower, but landscape don't move a lot, so therefore in combination with a statief you can make detailed pics with sharpnes.
Did you use ISO 400 on purpose to create some kind of effect?
Nope, on that particular shot I had literally just jumped out of the car (with my sweaty cycling clothese still one) and snapped the picture on auto. Same thing for the whole lot I took that day. So...no mysterious techniques.
Did you use ISO 400 on purpose to create some kind of effect?