Backing up puts you ahead of the game. You’re doing more than probably half of the people out there today.
Cloning your hard drive is a reasonable solution, but personally, I’m not comfortable with it because you can run into a few “gotchas” every now and then.
Gotcha #1: Manual updates can be error-prone
In your question, you say that you save anything new to flash drives. How do you identify when something is “new” and when it isn’t?
When you manually save anything new, you run the risk that you might miss something. Any kind of a manual operation that requires you to look for updated files or relies on your memory of what you did is error-prone.
It’s all too easy to overlook a file that you needed to back up.
Gotcha #2: What affects the hard drive can affect its clone
The other problem with cloning your hard drive is that certain types of failures can be pretty destructive.
The concern is that the clone remains vulnerable to various forms of failure that could be the result of the very types of issues that you’re trying to protect yourself from.
Gotcha #3: Backup frequency
I’m a little concerned with how often you’re cloning the drive.
No matter how you’re backing up, every six months seems like a long time between full backups.
At a minimum, if I had you do nothing else, I’d have you do your clone a tad more often.
No more gotchas
To be honest, I would add backup software (like Macrium Reflect) to your current strategy, and have it save backup images (periodic full and daily incremental) to an external drive. It won’t take much time to save everything that actually changes on a much more frequent basis. This way you’ll know for certain that everything that was changed was backed up – whether you remembered it or not.
If you’re looking for a more substantial change, I would then use the internal drive for additional space or speed instead of using it to create a backup of your hard drive.
But as I said in the beginning, backing up like you are is great. You’re way ahead of the game compared to a lot of people. I don’t want to necessarily say that you need to stop doing what you are doing, but just be aware of some of the gotchas that you might find.