I would recommend backing up your iPhone atleast once a week if not twice a week. Make it a habit and you will be better off for it.
And backing up to a Mac/NAS is perfectly fine and works. You don’t need iCloud backups for it.
But I use all non Apple alternatives for all that iOS backs up so I don’t really need a back up as such other than just for settings and app list. But I will be moving to Graphene OS soon.