Robin had so many chances for a 1 v 1 during Dressrosa, but Oda didn't give her one
She still had some great moments though. Her being able to stop crazy Cavendish and hold off Gladius did show improvement. Remember she couldn't ever restrain zombie zoro during thriller bark? Plus, she developed some new techniques and perfected gigantesco Mano.
Hopefully her experience with the revolutionary army is soon explained...
Also, she better develop Haki soon!