It can't do any harm I agree but I think you might be misunderstanding my reason for raising it, I wasn't mentioning it just to be disagreeable but that I'd be a little concerned that suggesting a back up might imply some sort of surety that just isn't there.
Take the examples you raise...
We don't know for certain that the device is fully synced to iCloud, it probably is but we don't know that for a fact.
Taking contacts by way of example. If you add a contact (that doesn't have chance to get synced to the cloud, before you sign out) and you do a back up, then sign back in to the cloud and subsequently end up losing that contact, restoring from the back up won't help because after the restore is complete it will sync with the cloud again and remove the contact all over again. The same goes for reminders, calendars etc
We don't know if the OP has spent all day shooting video, taking photos & is still uploading them to the cloud, probably not?
If they were going to upload to iCloud, then iCloud photo library would need to enabled. If iCloud photo library is enabled then your photos and video aren't included in the back.
Hopefully you can see my reasoning here.