This is by far my biggest pet peeve in the space. The "rule of thumb" that you need 2x RAM as swap. Even 10 years ago this "rule" was ancient and useless but it was always a constant challenge educating customers as to why, and that yes - we really did know better than your uncle Rob.
Once a server hits swap, it's dead. There is no recovering it other than for exceptional cases. If you are swapping out, you've already lost the battle.
I tend to configure servers with 512MB to 1GB swap simply so the kernel can swap out a couple hundred MB of pages it never uses - but that's really more to make people feel better than it really being useful at all.
Rules of thumb involving more swap than RAM probably date from decades ago, when Unix virtual memory systems were sufficiently primitive that the total amount of virtual memory you could use was just your swap space, not swap space plus (most of) RAM.
(The limitation came about because the simple way to handle swapping is to assign every potentially swappable page of virtual memory a swap address when you allocate it in the kernel. Then the kernel always knows that there's space for the page if it ever needs to swap it out and you're never faced with a situation where you need to swap out a page but there's no swap space left.)
2x RAM as swap is clearly bad, but I like having around 512MB to 1GB (on systems of basically any size); when you do start using more ram than you have, it gives you some buffer (as long as you actually alert on it). If you have a small memory leak, you can recover; if you have a large memory leak, you're going to run out of swap pretty quick anyway.
Once a server hits swap, it's dead. There is no recovering it other than for exceptional cases. If you are swapping out, you've already lost the battle.
I tend to configure servers with 512MB to 1GB swap simply so the kernel can swap out a couple hundred MB of pages it never uses - but that's really more to make people feel better than it really being useful at all.