What is the logic for Time Machine daily or weekly timestamps?

Time Machine appears to be running properly but I do not understand the timestamps chosen for the consolidated daily or weekly backups. Sometimes the times are early in the day and sometimes late.

For example:

2021-03-17-122438 (consolidated weekly)

2021-03-19-100136. (consolidated daily)

Work was done later on both of those days.

If I am trying to find a file I created sometime on the 17th (but changed / deleted sometime at least a week later. -- otherwise apparently would be lost) it looks like I would need to look at both backups.

I would think the timestamp should be the latest for any backup composing the consolidated backup.

Can anyone explain?