The just under 400 episodes of Sale that they're run are all that's available in an airable format (or that may be around period depending on the rumors about the Grundy vaults in Australia, although if they're there they'd need time consuming transfers). The January 1983 to July 1988 NBC shows have not been available for reruns as far back as when USA got the show in the early 90s. Except for one or two episodes, Buzzr and USA have now rerun the exact same set of eps, and GSN aired a subset of those. As far as I know, Sale is the most recent network series with significant portions of it's run missing. [Tangent: 2nd most recent, wildly, is Daytime Wheel, which is only complete from 1985-91].
In the online streaming era, they get exact data about who's watching what, when, and how (compared to the fuzzy math of Nielsen back in the day). The shows that have clicked with viewers they've basically run the entirety of save only a small # of eps (80s LMAD, Match Game, Supermarket Sweep, Classic Concentration, Press Your Luck) or have at least run significant portions of (Password Plus, Super Password, Perry and Eubanks CS).
In a couple of cases (Dawson Feud being the main one) a show has gone on so long that even if they've run a LOT of it, it still just scratches the surface. Since someone mentioned it specifically: They've aired approx 800 eps of Dawson Feud. Just under 200 shows from 1980, around 100 from 1981, all of 1982 [just over 250], the first 100ish from 1983, 40 from 1985, and scattered shows from the 1970s and the nighttime run. That's more than any show they've run other than Match Game, Classic Concentration, or Supermarket Sweep. But because that version of the show went on for nine years at 250 shows per year (with 1976/85 being half that) PLUS the mostly un-run nighttime run, it feels like they've aired significantly less than they have even though it's 4th in cumulative episodes.
The channel gets miniscule ad rates on traditional TV, and they only get a fraction of a fraction of a fraction of whatever a service like Pluto does in ad rev (if they get a cut at all). Compared to other similar networks Buzzr saves a lot of money since they've owned the overwhelming majority of shows they've aired (90s Newlywed being the biggest, longest-lasting exception) but they're still operating on a comparative shoestring, transferring things to contemporary media formats takes time and labor (and $$), and they have data from streaming on what people actually watch, and in general it's the shows they've already run a lot of.
