If you are settling the sale of your current home on the same day as the settling the purchase of the new home then making sure everything is ready for the day is important. Simultaneous settlement is likely to involve at least three or more banks (your buyers, yours, and the person selling to you) and potentially six or more lawyers (one for each bank and one for each buyer/seller).
Most banks arrange settlements through a call centre so you are just one of many files they handle. We often find that we have to make many calls to everyone to make sure everything everyone is ready on time.
It only takes one of the parties involved to not be ready and the whole thing gets delayed. This can lead to late settlement penalty costs.