Considering that the sith are all about stabbing each other in the back I would say that having only one person to worry about rather than an army is a smart move.

its kinda a dumb rule lets be honest here

The rule of two doesn't mean shit when your weaker apprentice kills you in your sleep. I wonder how much weaker the Sith became when Palpatine killed Plagueis.

Because unlike the Jedi the Sith can never work together because it’s in their nature to try to betray and take over

A backup plan would be good, otherwise your rule of of two is only a food poisoning / malfunctioning hyperdrive away from extinction ...

The Sith ruled without any true opposition for about 15 to 17 years. And even in that time, within the ranks of the Empire, the same betrayals and treachery were weakening it, without any of them being Darksiders. The Force just makes things bigger, it does not change the nature of things.

When there was many Sith, they ruled for centuries. Rule of two, took thousands of years to get one guy into power and that guy's rule ended after twenty years. Yeah, not seeing the "genius" here.

Ok but if you're a sith why take an apprentice? They're just a guarentee that eventually you'll be cut down. Just "be free" and dont care if the sith survive longer than you do.

Two there should be. No more, no less. One to embody the power, the other to crave it.

Ironically, the brotherhood of darkness taking on the jedi virtue of equality was likely the only way to combat the self-destructive nature of the dark side. Even with only two sith, the will eventually lose because no one man can be all powerful, and that lack of control is a killing blow to the rule of 2.

The Sith:

Maul to savage: im the master and you're the apprentice

Sith: We shall run everything, even the Jedi!!

What's even better? Having one Sith with an army of GONK Droids.

Palpatine: Sends Darth Vader to take the Jedi temple with the 501st

The Rule of Two might be the Best Option, but Sith Armies look Dope AF.

You forgot one huge flaw in the rule of two, a flaw that almost destroyed everything the Sith built as well as its history, Darth Gravid. He was a Sith lord in the rule of two who turned to the light and began to destroy all the work the Sith had done. This is why Sheev never had the knowledge or powers of older eras for one traitor, centuries of Sith lore and power gone in a blink of an eye. The only reason the Sith even survived this to get to Sheev is because Darth Gravid's apprentice killed him to stop him, even as two treason is part of the Sith.

tbf even the rule of 2 was destroyed by an act of betrayal in the end. Just seems like the sith were pretty shit at doing anything not related to just outright destroying everything.

At one time there where only two true sith in the movies, but we had many sith assassins. In general having just two sith isn’t exactly the best idea. I can support that with facts as well, when darth Vader was turned to the light and palpatine was killed there was no one left to continue sith tradition. it has effectively been destroyed with the killing of a single person. Where as the Jedi lived on through luke, had there been more sith the order could’ve persisted. Many people like to continue to say because the force was more powerful when there was two sith that it is the better option, problem is there’s almost always more than two dark side users at one time. That and the drawbacks like loosing the whole sith order with one death is just too great. Sure the rule of two may have allowed the sith order to “win” but it also destroyed it as well.

All out war tended to result in at best a stalemate so the rule of two which allowed a stealthy attack resulted in victory just like when Darth Revan or Vitiates empires attacked the Republic and brought them to their knees.