As "System Protection" / "System Restore" is intended as a tool to allow you to recover your "System" to a point in time, it should generally be employed for its' intended purpose and directed at your "system" drive / partition, containing your Operating System.
It's purpose is to allow you to recover from system file corruption like a bad or corrupt registry entry or an instance of a bad or corrupt driver and is not generally considered a viable backup solution.
IF it is your intent to protect all your drives and partitions against physical failure, corruption, accidental deletion or other catastrophic problems, then....
You might be better served by employing a robust backup / disk imaging solution instead.
Personally, I use Acronis True Image for this, but there are other solutions available ranging from "free" for personal use, to various pricing for local solutions or monthly / annual subscription cloud based services.
I'm not down-playing the benefit of System Restore, it can be a true life saver in some cases but I would never consider it as reliable overall protection.
It can fail and sometimes does. Nothing more depressing than seeing the message that System Restore was unsuccessful