TomK, thanks for that. What you didn't explain is whether you were looking for overnight permits or day hike permits. The situation is different between the two.
The 11 AM same-day permits are the overnight permits. If people get one of those, they still have time to get up to Whitney Portal and at least hike to Outpost Camp before dark.
The day hike permits are released at 2 PM for the NEXT day entry.
And then, if there are any of those less-than-full party permits, those become available, as you say, as soon as the party checks-in and picks up the permits they need. Their unused slots are available right away.
Of course, all of this will go away next week (Thursday, Nov 2), because the quota season only lasts through Nov 1. After that permits are available to all, with no quota limit ...until May 1.