Because once you press Rec, you have to wait for 4 mins to resume recording. If no one sits through those 4 mins, it times out and the recording gets saved.I use to record for longer periods and for all cams when I was a member.
Sadly, nothing happens during my time zone and people don't record that often ( May be less subscribers or lack of interest)
Picking and saving the right moments from a 24 hr timeline is the best idea IMO.Live Rec needs to be changed.