Hal's secret high: the pre-supper regimen interval
It's the sad little interval after afternoon matches and conditioning but before the Academy's communal supper.
Context
The scene sites Hal's secret precisely inside the regimen's day-shape: "after afternoon matches and conditioning but before the Academy's communal supper." The body's schedule is so total that even the private, off-grid act has to be timed to the one seam the drill-calendar leaves open — the athletic clock defines the negative space where a self can briefly hide.