If you use 14 days retention policy with 4 times a day backup job schedule, then you should have this:
5 days * 4 runs = 20 restore points + 1 Synthetic Full (21 restore points)
Please note that retention policy WILL NOT be applied for this chain yet, as the oldest restore point to be removed is the original VBK file which cannot be removed, because every subsequent VIB depends on this VBK file.
That said, when you initate another backup chain next week, the retention policy will be applied as soon as you have 20 restore points from the next week + 14 restore points for this week. Hope it makes sense.
Should more details be required, please have a look at this topic:
Restore Points and forward Incremental ?
If you want to have 1 week of backups, then you have two ways:
1. Specify 7 days of retention policy. Please note that Forward Incremental backup mode would keep 2x restore points, because of the reasons explained above.
2. Switch to Reversed Incremental backup mode and set the retention policy to 7
Thank you!