To the question of whether a profile (or updates to a profile) takes exactly 24 hours to be propagated through the system, I usually find that 30 to 36 hours is a more accurate number.
It depends on what time of the day you entered and saved the details, what time zone you are in, when the next update starts and when it ends.
If you happen to be actually entering or saving the profile right when one update is happening, then you wont see your profile be updated for at least 30 to 36 hours - 24 to 30 hours for the next update to start and then a few hours for it to run..
This is of course all from my own observations.