The timing marker pairs were designed to disappear when a new capture is recorded. Timing markers will generally lose their purpose when the original data it measured disappears. Of course, there is always the chance that the new data are perfectly aligned to the old timing markers, but we felt that most of the time this will not be the case.
As a suggestion to save time, you can quickly add timing markers by using the numeric keys on the keyboard as hotkeys.
trello ID: 59272a1905325ec6fa769772
trello data: 1517053060