I’ll second this, it’s absolutely a game changer. I’ve used handlebar mounted mirrors and the like but I’ll never willingly go back.
I tend to prefer helmet mounted and I glue them on which isn’t my favorite thing to do on a new helmet. It’s also a bit frustrating when you find yourself cycling in a country that drives on the opposite side.
I do find that on very long tours the week following I’m looking where I’d expect the mirror to be when I want to look behind me.
This reminds me of an oft recommended book "Digital Apollo". One of the driving topics is the human interaction component and the difference in designing a fully automated system versus one that is designed with an operator that can intervene. If I recall correctly, the book presents a dichotomy between the rocketeers and pilots (automate entirely and strap people on for a ride vs design a system controlled by a human).
I think they both have their place, but I think acknowledging it as a system design choice is so helpful even in basic business processes (how will I handle exceptions, how will the person remember to handle a rare exception).
I find myself thinking of this problem frequently. We have lots of modern words for it like observability but I think that removes one a bit from the actual problem.
I tend to prefer helmet mounted and I glue them on which isn’t my favorite thing to do on a new helmet. It’s also a bit frustrating when you find yourself cycling in a country that drives on the opposite side.
I do find that on very long tours the week following I’m looking where I’d expect the mirror to be when I want to look behind me.