John Oliver Excels in His Niche. He Should Stay There.

On Sunday night, HBO’s “Last Week Tonight” returned for the start of its fifth season, featuring host John Oliver’s satirical take on the news. If that summary sounds like “The Daily Show,” it’s not a coincidence. Oliver rose to fame as a “Daily Show” correspondent, and he hosted the program when then-host Jon Stewart was absent for eight weeks in 2013. A key factor that distinguishes “Last Week Tonight” from “The Daily Show” and its ilk, however, is that Oliver is on air only once a week, whereas most of his fellow TV comics are on every weeknight.

At its best, “Last Week Tonight” is wisely aware that its once-a-week format renders it poorly equipped to keep up with daily events, and it bows out of the headline-parody game altogether. Instead, episodes feature investigative-journalism-style reports on events that do not make American front pages but nonetheless have significant impact here and around the world. A particularly memorable episode shines a harsh light on the greedy practices of televangelists and features Oliver establishing his own “church,” “Our Lady of Perpetual Exemption,” to demonstrate the ease with which groups can take advantage of the tax-exempt status enjoyed by churches.

The Season Five premiere, however, seems to forget what makes “Last Week Tonight” special, as Oliver devotes much of the episode to satirizing the recent activities of President Trump. “Last Week Tonight” has targeted Trump before, and as before, the choice to focus on an oft-discussed element of the news hurts the show in two ways. First, it positions Oliver as a competitor with the plethora of other TV hosts for whom Trump jokes are bread and butter, most notably Stephen Colbert and Trevor Noah. Oliver’s writing team is great, and his delivery is often funny, but his eyes-popping-out-of-head incredulous shtick can feel un-humorously overwrought, particularly compared to Colbert and Noah’s calmer styles. Oliver’s presentation does not change depending on his subject matter, but when “Last Week Tonight” covers the same material as funnier comedians than Oliver, it invites unflattering stylistic comparisons.

The second way that covering Trump and other headline items hurts “Last Week Tonight” is by stripping the show of its educational power. Oliver’s satires of televangelists or the morally dubious world of debt-buying likely gives many viewers new information, and even when he covers foreign events of little direct importance to American life, viewers come away better-informed about the world than they were when they started watching.

True, the new segment about Trump is longer than most of its analogues (20 minutes to Colbert and Noah’s standard 5-10 minutes) and likely contains more information, but this extra time is unlikely to change anyone’s mind about Trump or to cause him to reverse any of the policies that Oliver discusses. When “Last Week Tonight” chooses issues of less prominence (and of a more manageable stature than the president of the United States), the effects of Oliver’s educational-comic sermons are palpable. He has arguably spurred a Federal Communications Commission policy reversal, changes in national civil forfeiture laws and New York City bail requirements, and many similar societal improvements. When “Last Week Tonight” lambastes Trump, on the other hand, the show becomes one of many, good for a laugh and not much more.

“Last Week Tonight” has demonstrated tremendous potential to bring about change, and its deep-dive investigative approach sets it apart from shows with a similar comic-liberal bent. Episodes that focus on relatively obscure topics are more common than the relatively disappointing ones like the latest episode. As long as John Oliver and company remember what they do best—in terms of both educating their viewers and changing the world—the show will remain among the most brilliant things on TV.