:prime time: [from TV programming] n. Normal high-usage hours on a
timesharing system; the day shift. Avoidance of prime time was
traditionally given as a major reason for {night mode} hacking.
The rise of the personal workstation has rendered this term, along
with timesharing itself, almost obsolete. The hackish tendency to
late-night {hacking run}s has changed not a bit.
-- The AI Hackers Dictionary