These are the only auto-CLIs I have experience of, and all are a bit, uh... different:
Various CCCs in Europe (Royal Bank of Scotland, Egg (owned by Prudential? I forget), MBNA, to name a few) - would auto-CLI me by a massive amount every time I came close to maxing my card out. Even if I wasn't showing much sign of paying more than the minimum in any given month. And even if, say, for example, I'd been doing cash withdrawals on a far-too-regular basis. Classy.

Those auto-CLIs can only have been based on overspending and general deterioration in credit profile, I'm sure. That was a few (as in, 'a lot of') years ago now, though... hopefully that kind of practice is far from common these days.
Bank of America - husband's first auto-CLI ($5,000 up to $11,000) came after I PIF'd the (maxed-out) card for him, on the following statement. The card was then not used AT ALL for, ooh, six months, before we charged about $10 to it, and PIF'd. At which point they auto-CLI'd from $11,000 to $16,000. Those auto-CLIs... well, his scores had improved both times, and his util obviously went down hugely the first time, and was then down to a fantastically low amount by the second auto-CLI. I think a bit of credit-watching AND monitoring of usage of that actual card happened there - as in, I doubt the second one would have happened if we hadn't woken the card from its slumbers by charging a tiny amount to it.
Target - after around 9 months of consistently paying off FAR above the minimum payment, and not actually using the card to buy anything at all, they auto-CLI'd from $1,700 to $2,600 because of his 'excellent handling of his account', or somesuch.
Banana Republic (GEMB) - I hadn't used my card in 6 months and it had been PIF'd for at least 2... uber-generous auto-CLI from $500 to $600. Whoop-de-doo!!!!

Capital 1 - auto-CLI'd me like they said they would, after I'd done that whole credit steps thing.
Not sure any of that helps, but... all I know is that different lenders must base their credit line increases on VERY different factors.