I like the PDF as standard print job format setting, I just want to know, why does LO Writer leave a blank page after the index/summary but not after the first page, which makes more sense to me, because when printing the first page (which is usually mostly white, you can see what’s written at the next page if the paper is thin enough).
Look for the page style layout: only right, maybe?
“index/summary”, is the Table of Contents?
Right now it’s for both pages: left and right, but it’s shown as right in book view. I tried as only left, but it includes the page before the first page, which doesn’t make any sense to me.
Yes! That was what I meant!
If you want an automatic blank page after the First Page then in your template, modify the page style in the Organiser tab so that the next style is Right Page. You will also need to tick the box Print automatically inserted blank pages in the Options dialogue from Tools > Options > LibreOffice Writer > Print.
In Western documents First Page is always a right page (recto). If this is followed by a Right Page then an automatically generated blank left page (verso) is inserted for printing as you cannot physically have two right pages in sequence.
For pdf, you might not bother if it is only intended for on screen use.