Blindspot Mirrors vs Looking over your shoulder

[Pickled Piper]

What is the latest thinking on glancing over your shoulder before changing lane? It's something I always do rather than relying on mirrors. However, my daughter who recently passed her test, told me she was taught to use the blindspot mirrors fitted to the instructors car.

I'm planning on teaching her to glance over her shoulder. Perhaps I should buy some blindspot mirrors for myself?

PP