The worst part of RDR for me is not any specific part but the overall "Rockstar Games" story progression. The story beats are so slow and inconsequential to the central plot; a lot of them are just excuses for level design and content. Mexico for me is at least more interesting in terms of themes than the West Dickens missions that just drag on and on. Armadillo was honestly as poorly paced as Mexico was, it's just that novelty of playing the game hasn't worn off yet at that point. Mexico just happened to be after an overly long first act.