The only major thing that she achieved successfully in the series was deposing Siuan and becoming Amyrlin. No small feat on first look, but when you factor in the Black Ajah and Mesaana's support, it's not all that. Though at least by noticing Min visiting Amyrlin's study at the start of TSR and remembering her connection to Rand and the Supergirls, Elaida showed a working brain, one of the rare times in the series. But as an Amyrlin she did pretty much all blunders possible, and the only thing she did right was sending Beonin and the other spies to the rebels. Everything else was a disaster. I don't think she would've been a good Amyrlin at any time, she lacked way too much qualities need for a good leader.

It certainly would've been much better if she were a more worthy opponent for Egwene and not such a complete caricature in Books 6-12. She made way too many dumb decisions to remain even a remotely threatening opponent.