In other cases, though, much of the work of clearing that high bar falls to the heaving, struggling patron.

Making each course as different as possible from the last is not just a chance for chef to show off; it’s necessary to keep the diner’s attention. During an epic evening at Saison in San Francisco, I was often amazed by the way Joshua Skenes coaxed extra flavor from his ingredients through ancient means like dry-aging, curing, fermenting, smoking and grilling over fire. But some of the courses, more than 20 in all, were repetitive in ingredients or preparation, and others felt like padding. I walked out dazed when I could have been dazzled.

Wylie Dufresne’s vision has been consistent from the day he opened WD-50 in 2003. But a recent tasting menu there was, perhaps, consistent to a fault. Almost every plate was composed the way Mr. Dufresne used to put together his appetizers and entrees when he still served them; nothing broke the pattern. Rather than using the tasting menu to tell a different story, WD-50 tells the same story more often. Mr. Dufresne is one of the least boring chefs in the country, and his plates never lack originality, but the shadow of monotony loomed over the meal by the end.

If a meal goes on for hours, even radical costume changes from course to course may not be enough. Daniel Humm has rounded up an amazing variety of ideas for his new $195 tastings at Eleven Madison Park. But I wasn’t sure why he was presenting so many at once. Some of the menu was based on classic New York dishes, but a lot wasn’t, and I struggled to find a single point of view.

The shapelessness of certain tasting menus might be blamed in part on a broken feedback loop. A restaurant that sells appetizers, main courses and entrees quickly learns which ones customers like. But one-bite dishes rarely come back to the kitchen untouched, so the chef has little chance to learn what customers think. Asking “How was everything?” of somebody who has just consumed 27 items isn’t likely to produce constructive criticism.

These restaurants can deviate from old-fashioned notions of hospitality in other ways. The ideal of serving a hot meal has been increasingly a lost cause, given how quickly a morsel the size of a cat’s tongue will cool.

The strangest of all the anti-hospitality gestures, though, is the delayed-bread power play. For centuries, good hosts have placed bread on the table. Blanca, Momofuku Ko and other restaurants do the same thing, and their bread is often superb, but the meal is about half over before it appears. When I’ve asked about this, I’ve been told that the chef didn’t want diners to fill up on bread. When did it become a restaurant’s job to keep its customers from feeling full?