John R. Ellis wrote:
You may already know about this: According to this post, a 1:1 preview will not be discarded unless the width of the standard-sized preview chosen in Catalog Settings is less than half the width of the 1:1 preview.
I did not know that - thank you. I retested discarding 1:1 previews after dropping standard preview size and it worked just dandy (and immediately) - not broken after all.
Thanks again John .
Rob