I haven't done that in almost a decade know, ever since Google algorithms made it nearly impossible to rank them anymore.
Personally, I did the archive.org method, where I would trace all the sub-pages and recreate a site with content for the pages that seemed to still generate some traffic from pre-existing backlinks on other sites referring their readers to those sub-pages.
There really wasn't a science to it, but it's definitely not as lucrative these days as it was back then, especially with the latest PPC fiasco.
Unfortunately, I feel like the people doing that today are fighting an uphill battle and trying to paddle upstream with rapids.
In my opinion, the only ones still making money with the archive.org method, generally run a marketing service selling blackhat backlink campaigns in bulk and live in a region of the world where the economy allows them to live comfortably on just a few hundred dollars per month.
Fiver.com appears to be one of their main sources of selling those services for $5 to $15 per 500 to 2k backlinks spread across their huge portfolio of sites. generally, there sites are not targeted to specific niches and catch-alls with articles in various categories. Now days, all spun with AI assistance on the fly, to rapidly deploy the content and links. I've seen them output 2k articles + links in them in 48 hours. 500 to 1k, they can do in 1 day (For multiple clients in the same day).
So essentially, their fiverr gig with just 1 client per day (Average) generates $5 to $15 x 30 days = $150 to $450 per month, not counting the fiverr up-sell/add-on options taking it to $20 to $30 per gig, or compensating for larger flux and repeat client days (e.g. 3 to 8 gigs in 1 day).
Note: While most are not niche targeted, once some generate enough revenue doing it, they do start to build out a niche portfolio where they have high demand clients, specifically to cater to a repeat, long-term client contract. Effectively making it a full time job and they start bringing on family and friends to help with some of the over-flow work load.
As for the casino parked pages, while doing professional appraisals and running through comparable sales reports (Daily), I see them all the time. Not sure how lucrative that model is, but it's definitely a popular parking technique in Asia.
That's my experience with it anyways.
others may have different experiences.