Which PgBackRest policy for differential backups in PostgreSQL

I set up pgBackRest and PostgreSQL configuration in two different servers. I set up with crontab one full backup a week and one differential backup a day.

0  1   *   *   0     pgbackrest --type=full --stanza=stanzaname backup  
0  1   *   *   1-6   pgbackrest --type=diff --stanza=stanzaname backup

I set up retention as below to save disk usage:

repo1-retention-full=2  
repo1-retention-diff=1
repo1-retention-archive-type=full

Is it possible to ensure PITR to cover up to 2 weeks with this retention configuration? If yes, is there a benefit to set a differential retention more than 1? Because keeping more differential backups could consume a lot of disk space.