Some type of brimmed headwear is not only good for deflecting ejected spent cases, it can also help significantly to mitigate blast/concussion, especially indoors or if a line-mate is using a very directed brake/comp.
That said, it's *_also_* possible for spent cases to be ejected and deflected in some REALLY WEIRD ways. I, as well as others, have had some really weird experiences (
https://www.thearmorylife.com/forum/threads/a-sure-painful-experience.8722/ ).... As I detailed in that thread, my weird one was at an indoor range - the case managed to bounce over the top of my shooting glasses (mind you, my shooting glasses essentially have lenses twice as thick, because there's a prescription insert behind the ballistic lens), and landed on the top of my cheek, trapped there between my lower eyelid and the inner lens.
This was WITH a "traditional" long/curved-brim (not the currently fashionable flat/short bill) ballcap on....the spent case somehow bounced off the stall wall to my shoulder/upper arm, up under the bill of my ballcap, and then into where it finally came to rest.
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Aside: I have some friends who really like the NOTCH ballcaps -
https://notchgear.com .
They don't work for me, and I also know other folks for whom it doesn't work, but for some, this may be a solution for hat-brim/glasses-frame interference.