If "The Measure of a Man" plays as a rebuke to "The Schizoid Man" in terms of artificial-intelligence themes, then so "Time Squared" plays as a rebuke to "The Royale" in terms of procedural sci-fi mysteries. The crew is stunned when they discover a duplicate of an Enterprise shuttlecraft adrift in the middle of empty space, and inside the shuttle is a duplicate of Captain Picard.
Strangely, one of the reasons "Time Squared" works so well is because it comes fairly early in the series' run, at a point when the show hasn't been time-traveled to death. Here's an episode of TNG that is not jaded by the fact that a duplicate of Picard has crossed through time and brings with him crucial information about the Enterprise's near future. The story depicts the duplicate Picard as a harbinger; Picard himself is unsettled by the sight of his twin lying in sickbay, to the point that early on he flat-out refuses to accept that the doppelganger is in fact the same person. When the crew discovers the duplicate Picard's shuttle log, they determine the duplicate is from approximately six hours in the Enterprise's future; there's a disturbing video recording that shows the Enterprise being destroyed.
The episode is a triumph of mood and tone, in no small part because of Dennis McCarthy's ominous musical score, but also because the crew reacts with genuine awe and concern to this bizarre situation. The way the mystery is slowly broken down allows us to become fully immersed in the story. The notion that the duplicate Picard has an internal biological clock that is knocked out of whack is intriguing, even if it is the only such example in Trek time-travel annals. The closer to his time we get, the more normal he becomes, and yet we always get the sense that he's trapped in an unalterable loop where his actions have already been preordained.
Best of all, the episode is content to let a mystery be a mystery. The vortex that traps the Enterprise (which resembles an inside-out tornado in space) seems to be governed by some form of intelligence, but the story never spells out exactly how or why. And unlike "The Royale," the episode is able to make unanswered questions part of its appeal, rather than a lumbering mess.