The game is just a bit too expansive, really, and I'm slightly put off by the amount of side missions and other bits and pieces that I know I'm not going to find and complete. I've decided to not worry about this, though, and my primary aim is to complete the story, ignoring the trophy list and multitudes of icons on the map. I do keep getting distracted by the strangers and herbs, though.
According to the Rockstar Social Club, I've now completed 36.8% of the game. I'm not sure if that's just the main missions or everything. Still some way to go, whatever.