Thanks a lot for your replies!
Yes, I understand that sectors get bandboxed/combined at night but if, I remember correctly, the whole discussion that prompted me to post on here started while talking about the existence or not of Traffic Load Prediction Devices in area control centres around Europe that could give you a 24-hour dynamic picture of how the traffic is going to be and what kind of traffic you are going to have (outbounds, inbounds, crossing, ...).