When I choose to discard 1:1 previews after 1month, no other small preview is created? Why?
Would be smarter to leave a smaller preview in place, wouldn't it?
Smaller previews are left in place. Lightroom shows you one of the so-called 'standard-sized previews' when you view an image. That is a pyramid of previews ranging from a small thumbnail to 'loup view size'. The 1:1 preview you mention is something extra. You can build it on import, or Lightroom will build it when you zoom in to 100%. The 1:1 preview is not part of the standard-sized previews, so if you automatically discard them after a certain time, then the standard-sized previews are not discarded.
Please note that if you manually delete the 'previews.lrdata', then you delete all previews, not only the 1:1 previews!
Thanks for your answer . I always create 1:1 views on import, discarding them after 30 days.After that many views disappear - nothing is left in place - after this period.I never threw away "previews.lrdata".
I've been working like this for many years. I don't understand what could be happening.