acresverdebecause they sit in a vertical plane, once every year or so is a good idea to rotate 180’ then 90’ next time and 180’ next, this stops woofer cone sagging one way which can lead to the coil just scraping slightly in the gap and wearing the very thin lacquer off then shorting out.
Why, pray tell, does one "...rotate the driver..."
Kef B139’s were famous for it. I do my ACI SV12’s every year when I remember.
Cheers George