Multiple targets with different run frequencies

I have two volumes, `btr_pool` on a ssd and `backup` on a hdd. The server is in a living room so I want to keep the HDD usage as low as possible, which means a backup at 3am only. I also want to keep local hourly snapshots on the SSD. I run this config with an hourly cron:
```
timestamp_format long-iso
preserve_hour_of_day 3
preserve_day_of_week monday

snapshot_create onchange
snapshot_preserve 30h 15d
snapshot_preserve_min 24h

target_preserve 35d 5w *m
target_preserve_min no

lockfile /run/btrbk.lock

volume /mnt/btr_pool
snapshot_dir snapshots

subvolume @
target send-receive /mnt/backup/snapshots

subvolume @home
target send-receive /mnt/backup/snapshots
```
I thought the backup would only run daily, but the HDD wakes up hourly.
My current workaround is to have an hourly `btrbk snapshot` and a daily `btrbk`. I added the `lockfile` by fear of a race condition. It seems to work correctly, but is there a better way?