This is the part of the TV season when the luster of everyone thinking life was sweet gets rubbed down to the awful truth: Even in the midst of a great season, shows have to die.

Usually, this period begins much earlier — like the week after most of them debut.

NBC’s “Mike O’Malley” was the first show to get canceled, followed shortly thereafter by CBS’s “Work With Me.” No problem there — most everyone thought they were lousy. Much more difficult — and telling — is when shows with potential get the ax.

When Fox killed Chris Carter’s “Harsh Realm” and “Ryan Caulfield: Year One” Monday, it raised some eyebrows. After all, both shows aired with relatively good reviews — more so for “Harsh Realm” than “Ryan Caulfield,” but both of them were positively received on the whole. The former got a meager three airings and the latter only two. Immediately, Carter suggested that Fox blew it with his show — that the promotion was nonexistent and the support from management was never there.

He’s definitely right on the first count and if he’s right on the second, it almost certainly means that his mystique is over at the network and, barring a miracle, this is indeed the last season of “The X-Files,” the show that put him on the map and has helped define Fox.

No time like now to bring up the old but apt slogan: What have you done for me lately?

This is how the television industry works, though, and even a massive Internet campaign that is most likely right around the corner won’t save “Harsh Realm” or Carter for that matter. Networks are ruthless when they want to be and stupid when they need to be. They become so when it best suits them. For Fox, the stupid part came when it had to play along with Carter on his wonderfully bleak but woefully witnessed second series, “Millennium.”

What could Fox do back then? Tell one of the hottest producers in the business that they were yanking his failure? No chance. Like many networks before it, Fox figured Carter would hit one out of the ballpark next time, and they couldn’t risk him doing it for someone else.

But when “Harsh Realm” reaped some of the lowest ratings Fox has ever had on Fridays (lower than “Millennium” even), that sealed it. The question is this: Has Carter lost his touch, or did Fox bungle “Harsh Realm” from the start and then fail to nurture it?

Network identities, their cultures, rest on the answer you get. Fox has gone from nurturing new shows — mostly because they had no choice — to being a network willing to pull the plug almost immediately. This season, Fox has a new entertainment president in Doug Herzog, who came from MTV and Comedy Central. He didn’t green-light any of Fox’s fall programming so he’s not emotionally invested in them. Carter even told Daily Variety that Herzog wasn’t a fan of “The X-Files.” That’s a bad sign.

The fact is, “Harsh Realm” was confusing. No question about it. But so was “The X-Files” — maybe the most confusing series ever. But it became a hit through patience. And “Ryan Caulfield” at the very least offered a fresh take on the tired and nearly dead cop genre. It was surprisingly good and had potential. Now — gone.

It’s clear that this season Fox’s culture is one of low patience. But perhaps the blame should be shifted off the shows and onto the network itself. Fox eschewed the traditional premiere week concept this season — as it has done much of the past. Instead, knowing that it had baseball, which would preempt some new shows, it chose to roll shows out slower, in dribs and drabs.

So much for that plan. How can a network bungle the most hyped show of the season (“Action”) so that it airs two back-to-back debut episodes and gets beaten unmercifully by a rerun of “Frasier”? That’s as unexplainable as it is inexcusable. The network has also failed to build much of an audience for “Get Real,” an unorthodox series that needed particular attention paid to the promotion, so audiences would grasp what it was trying to do.

Although “Action” will return, the fate of last season’s budding hit, “Family Guy,” is less clear. Both have been pulled from the November sweeps schedule.

The cancellation of “Harsh Realm” and “Ryan Caulfield” could signal that Herzog wants to put his own stamp on the network. But the move is disturbing in that it seems a knee-jerk reaction. And what does Fox have to replace these shows with? There’s a backlog of reality shows, but that’s a direction Herzog said the network was moving away from.

Fox, of course, is not the only network making difficult, sometimes mind-boggling decisions. When ABC presented “Once and Again,” it was clear to most critics (though that’s hardly a good barometer) that it was the best new show the network had. By putting it in the “NYPD Blue” spot, wouldn’t that cause problems down the line if the show was an actual hit?

In essence, ABC said it would deal with that when the time came. The time came and ABC ended up alienating “NYPD Blue” creator Steven Bochco by first suggesting it might move the venerable cop show, then finally pushing its debut back until January.

ABC’s network identity has always been the quick-hook coupled with no brains. It has ruined many a fine show (“My So-Called Life,” “Murder One,” “Relativity,” “Cupid,” “Nothing Sacred,” and many, many more) by putting them in impossible time slots or simply giving up on them.

The network had no idea what to do with “Who Wants to Be a Millionaire” despite the fact it fascinated a nation. The show is coming back next month for sweeps, but that initial buzz is gone and the gap has allowed other networks (like Fox, with “Greed”) to rip off the idea and steal its thunder.

Not every move is a blunder, however. Many shows get pulled precisely because they are bad. ABC yanked “Wasteland” but says it will give it another chance (hopefully that’s a typical network lie. Also coming off the schedule, deservedly, are NBC’s “Suddenly Susan” and CBS’s “Love & Money.”).

Most shows die because they deserve to, but in a world where, up until this season, having a plethora of quality was unheard of, killing one great show unnecessarily caused gaping creative holes that were rarely filled.

It bears watching whether networks will have patience or panic. NBC has a gem in “Freaks and Geeks,” which has aired only twice because of baseball and rests in the Saturday night death slot. That’s a dangerous future.

Fox has said it will be patient with “Action” — a show it had to know would appeal to a very limited audience — but we’ll let the network’s own actions speak loudest on that.

We are about to see more cancellations. These things tend to come in droves.

If the networks can muster an equally impressive midseason maybe the damage won’t be so severe. But the fear is that all of the surprising good quality we’ve seen from the fall premieres will be squandered by networks in an all-too-familiar squeeze of their hair triggers.