Quoted from Anonymouse:Press A to make your horse go faster. In the end I have to say that it's a good game but it's artificially long. Too much riding around.
I agree there is a lot of riding around, but try not to rush through the game and I believe you will enjoy it more. Just riding around, enjoying the incredible scenery, maybe there's some deer in the distance? Go hunt it with your bow and save the hide for crafting a satchel upgrade. Take alternate routes, discover mystery strangers in need, etc.
This is like the opposite of pinball which is constant fast-paced action. I have to "adjust" my mindset when transitioning from pinball to RDR2 since they are so different. I love them both but for completely different reasons.