These are the rrdtool definitions that are used:
'RRA:AVERAGE:0.6:5:720',
'RRA:AVERAGE:0.6:60:360',
'RRA:AVERAGE:0.6:300:576',
'RRA:AVERAGE:0.6:3600:336',
'RRA:AVERAGE:0.6:21600:3000',
'RRA:AVERAGE:0.6:604800:520',
Which, I think, means: keep 720 5-second averages, keep 360 60-second averages, keep 576 300-second averages, etc.
It looks like for the 24-hour view it uses the 5-minute (300/576) definition.