> Sometimes they can't help that, because CD track indices must fall one
> 1-second boundaries.
Not quite. The table-of-contents specifies track start-points as
an integral number of `subcode blocks' of 1/75 second each.

> So if the two are really close together, sometimes
> they have to make a choice between letting a split second of the prior
> song appear, or cutting off a split second of the next song.
Each track must last at least 2 seconds. This is because of the way the
Red Book specifies the most primitive track-seek mechanism: the P-channel
must mark at least two seconds before a track change occurs so a dumb
CD player can try to hit roughly the right spot by dead reckoning using
the absolute subcode block number given in the TOC, then whizz forwards
looking for where the P-channel bit changes from 1 to 0.