system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Is it fair to say that a millenium of Sith planning led to only 20 years of actual victory?
gpt
eh not at all because Sidious ruled for 20 years but ultimately he did defeat the Jedi.

There are literally no Jedi left besides Luke as of right now.  Until Rey or Finn start doing something there seem to be quite a bit more dark side force users.  Kylo, Knights of Ren, Snoke.  

So, no... it isn't fair to say.