One of the reasons television series have become so hard to remember — as opposed to being unmemorable — is that viewers now have to wait a lifetime for them to return from one season to another.

Next week, the critically praised Netflix series “Mindhunter” returns — after a two-year absence. Ridiculous. Even if you loved this show — and people became engrossed as FBI agents Holden Ford (Jonathan Groff) and Bill Tench (Holt McCalanny) matched wits with some seriously damaged criminals — you probably have forgotten all about it. There are so many viewing choices available now that it’s much easier to pick up a new series than put yourself through a refresher course to remember an old one, especially a show that’s only had one season.

“Mad Men” was one of the first shows to pull this stunt. After winning four consecutive Emmys for Outstanding Drama Series, the show held its adoring, aspirational audience hostage for nearly two years, between 2010 and 2012, before a new episode aired. The ratings, never great, plateaued in Season 5 and then declined. As for its professional standing, the show never won another Emmy for Outstanding Drama Series.

When “Game of Thrones” took nearly two years off between its seventh and eighth seasons — presumably to film those 80-minute episodes that were lit by kitchen matches — fans were frustrated, but they’d gone too far with the show to turn away. They watched to the bitter end, delivering the show’s highest ratings.

It’s much easier to pick up a new series than put yourself through a refresher course to remember an old one.

But very few shows enjoy the passionate following unique to “Thrones,” whose popularity had its roots in the novels written by George R.R. Martin.

The next season of “Ozark,” last seen on Netflix in the summer of 2018, is not scheduled until next year. The Jason Bateman money laundering family drama worked well in the summers when nothing else was on, but who knows if people will even care with the 400 shows that will likely premiere between now and then. “Homeland,” which last aired in February 2018, won’t be back for its eighth and final season until February 2020. Similarly, “Better Call Saul,” last seen in October 2018, won’t be back for its fifth and final season until sometime next year. Just fold the tent already.

The worst offender, of course, is “Westworld.” After taking 14 months off between Seasons 1 and 2, which ended June 24, 2018, there is no date yet for the Season 3 premiere. The plot on this HBO series is so intricate, no one’s going to remember anything about the show.

Can the networks and even the streaming services afford to be so casual with the audiences, “ghosting” them for long periods of time while waiting on production and actors’ schedules to align? It seems suicidal.

Then there’s the case of “Downton Abbey.” The British import knew its audience of 13 million would be clamoring for new episodes after the holidays and had a new season ready, for six straight years, in January. The culmination of that steady storytelling and reward for all that viewer loyalty is the extension of the series to a big-screen feature film, opening in September.

You can call that an upgrade.