Here is my experience with the Borderlands franchise:
I've played through the first game (plus all DLC) at least one full time. Maybe twice? (I can't remember if I did a full playthrough a second time in prep for playing the sequel or if my original playthrough was at least in part for that purpose.) I have played it at least 1.5 times, given that I've done another one or two aborted playthroughs that ended somewhere between a quarter and a half way through. So, let's go with somewhere between 1.5 and 2.5 times through the first game.
I've played the second game at most about halfway through, maybe, before just abandoning it, on probably two or three attempts at it. I remember at least getting as far as the Tiny Tina D&D-inspired stuff (not to be confused with Tiny Tina's Wonderlands, which is similar, but not something I own or have ever played) the first time.
I've played, according to Steam, 40 entire, whole minutes of Tales from the Borderlands, which is a Telltale-ass Telltale game based in the Borderlands universe which, for whatever reasons, I pretty much completely bounced off of, even though I generally liked those old Telltale games (for the most part). I may give this one another shot, someday.
I own, but have not yet touched at all, The Pre-Sequel and Borderlands 3. I am in no great hurry to play them.
I don't own any other Borderlands games. I have pretty much no interest in buying any more Borderlands games (with the possible exception of Tiny Tina's Wonderlands).
I have less than zero interest in seeing this apparent piece of shit Borderlands movie. I had no knowledge that a Borderlands movie even existed, prior to starting to see all the articles popping up in my Google News app talking about how poop it is.