That's probably not right with today's RAM sizes but I'm not sure what the current rule is. I just go with the Ubuntu installer default but I don't know if that's just a fixed number or computed in some way from amount of RAM available.
Which was always a dumbass rule that made no logical sense.
Like, I remember a time when I had 4 GB of RAM and had my swap set to 8 GB. Then I upgraded to 16 GB of RAM. Theoretically, I shouldn't even need a swap file anymore, since my old setup would max at 12 GB and yet I never had OOM problems, but that "rule of thumb" would dictate that I should increase my swap to 32 GB.
I remember when I first came across this rule when getting into Linux for the first time. If memory serves, I had 256MB of RAM, so I set swap for 512MB, which seems perfectly cromulent.
The other part was that it kinda matched the money you were spending on the machine.
The guy with 128MB of ram could likely afford to spend the extra disk space on a swap partition then the guy stuck with just 32MB.