As a photographer, I agree. Make multiple copies of the files onto the main editing computer, followed by then also backing up direct from SD to the NAS. Never format or delete your cards (the originals) before you are dead sure you have several backups visibly uncorrupted.

I may be paranoid because I used to handle footage for VFX pipelines and you just do not mess around with those kinds of files. If you lose footage, you are in big trouble.