I usually use a lock because I don't want my suitcase to open up in transit, but I hate having to keep track of the keys. One time my lock broke, so I used a twist tie. I just found these carabiner rings that are small enough to fit through my zipper lock. Is there any reason not to use them?
I never back anything valuable. Usually, it is just clothes and toiletries. And for years, I have used various things like carabiner rings to close up my purse or backpack.