should I do apply-log to all output folders?

When I ran

innobackupex /db-backup/ -u root -p password

I got output in /db-backup like below (successful, of course)

ls /db-backup/

2017-11-05_06-25-51 2017-11-05_06-28-58 #recycle
2017-11-05_06-28-21 2017-11-05_06-30-37

I’m thinking of creating a for loop that gets db-backup-date +%F_* and apply-log to each folder just after ran full backup on crontab

Is that the right way to do this?

You need to prepare against entire backup folder simply.