In the flashback that tells Roger's story in the Wano arc, it can be seen that Shanks and Buggy didn't go with him to the last island, Laugh Tale. At that time, Buggy was really sick so he was left on the island right before Laugh Tale. But Shanks, who was healthy, could have joined the crew, but he chose not to. He decided to take care of Buggy instead.

In the newly released One Piece chapter 1082, Buggy mentioned that Shanks originally intended to go to Laugh Tale, but he changed his mind for some reason. Most likely what made Shanks change his mind was because he had heard a lot from Roger before.

At that time, there was a scene where Shanks cried while hugging Roger. Young Shanks' voice actor, Nobunaga Shimazaki, once commented on this scene. He said that this scene was the turning point in Shanks' life at that time. Could it be that Shanks never intended to go to Laugh Tale until now and left that wish to Luffy?

Source: Facebook/One Piece Indonesia