Backup and storage - as separate PDF files or as one PDF container/portfolio?

Hello

Forgive me in advance for my English, it's not my mother tongue.
In terms of backing up and storing PDF files, which option is better?
Backing up separate PDF files or merging them all into one PDF file/PDF portfolio, that will be updated periodically to add new pages to it?
In terms of convinience, the option of one file is better for me.
The question is what is better in terms of backup and storage.
My assumption is that in the form of many files, there may be a situation where I don't open the files at all and over time the files may be corrupted (I'm exaggerating on purpose) compared to one file that once in a while will receive a refresh because I'll add more pages to it. On the other hand, updating the file once in a while might create a situation where it gets corrupted too one day, and I will lose the whole data (I may be talking nonsense, that's why I ask)
I would like to have an answer.

Thank you