Any backup strategy needs to be created to deal with (identified) risks.
When traveling I keep the images on my cards until i get home.
I also download on my computer and occasionally an external HDD (depending upon the length of the trip). On extended trips I use multiple HDD and keep them separate.
I am protecting against loss, hardware failure, and my own stupidity when I accidentally format a card in the field.
At home I have multiple copies of all images, and a copy in the vault (though any off site would work). Protecting against hardware failure and accidentally deleted images by multiple backups and the offsite copy protects me in case we lose the house (fire).
As a last resort I have a copy in the cloud (mostly because I got a good deal).
As a final note, I look at my backup strategy and feel good about it. I can sleep at night, I don't worry about my images. Yes it takes me a bit of time but not much extra to manage this. In the unfortunate event I loose all copies of my images, I know I have done everything reasonable to protect to them. Could I do more? YES, there is always more but at some point the added safety of another layer of backups is simply not worth it (to me).