is this option sufficient?
This is not a question that can be answered generically. Only the person doing the backup can really know.
And the way you know, pretty much, is if you were to lose everything you've worked on, uploaded, etc., between your last full or differential backup and the next differential one that has not quite yet occurred, would you be ready to scream, rend your garments, and snatch your hair out?
There are environments that have immense amounts of work going on every minute (think something like the ordering system on Amazon.com) where, if they were to lose the orders placed in the last 15 minutes, it could mean the loss of tons of money and a lot of angry customers. They're taking backups far more frequently than once every couple of days, because they need to.
Contrast that with most home users, who mostly browse the web, write email, and similar, maybe creating a new word processing document every once in a while. Their need to do full system image backups (or incremental/differential backups afterward) is far less frequent. On my own machine, I do a once a month full system image backup, and use two different backup drives, one for the even months and one for the odd. I do not generate enough new material between those backups such that I'd have a fit were I to lose what I have done. On the odd occasions where, for instance, I might have been on vacation for several weeks and just uploaded thousands of photos that I wouldn't want to lose, I will then take an "off monthly cycle" full system image backup, tossing the previous one for that month. I have no real need for any differential/incremental backups.
What is "sufficient" is solely determined by what it is you're trying to protect and how much material you could, in theory, afford to lose. The person doing the backups needs to have thought about this in order to set up a protocol that fits
their needs.
There is no one-size-fits-all backup protocol.
