Thanks, Idris, yes, I'm fully aware of folders and bookmarks 🙂 I do a huge amount of medical research, and I have hundreds of folders and subfolders.
If Safari isn't designed to leave x number of tabs open semi-permanently, they shouldn't have extended the number of tabs you can have open at the same time on the Air 2. The original Air had only a limited number of tabs, and your 'New Tab' option was greyed out once you'd reached that number. I can't remember how many it was, but I think it was around 50, or maybe 100. Air 2 gives you new tabs up to x250, so it hardly seems fair that it doesn't seem to like having tabs open either in quantity or for any length of time. My Air 2 is 128gb, so it isn't like storage is an issue.
Mine were all absolutely fine until I started re-organising them in blocks after a particularly diverse research session. Then it deleted most - not all, it left me the last seven - of them. It's never happened before, and it hasn't happened since. I haven't bothered re-organising open tabs in the pinch-screen, where it shows you a whole screen of open pages when you pinch any Safari page, I just move tabs individually.
It must be a glitch.
Kindest regards,
Angel 153