The seven routes of the Grand Line, as explained by Crocus, have the same difficulties.
But the thing that Crocus didn't say is that al least one of them (of course I'm talking about the one followed by the Straw Hats) is most likely the best one to follow. The reason is easy to understand: during their journey Rufy and Co. reached Drum and Water 7, the islands in which the best doctors and best shipwright live! And of course they took one doctor and one shipwright. Rufy was super-lucky in choosing that route.
But then a theory was born in my head: what if... What if actually the Straw Hats didn't follow a single route? It would explain all that luck. Maybe Drum and Water 7 weren't part of the same route. There are two possible moments for this theory.
- In Little Garden Sanji rescued an Eternal Pose for Arabasta. Nami's Log Pose never pointed to Drum. Since le routes are not straight, the Straw Hats can have "invaded" another route during the journey to Arabasta, approaching Drum which was part of this second route. However of course Arabasta was part of the original route because it was the final destination for Vivi.
- After Jaya, Rufy "jumped" on Skypiea, which stays on a travelling cloud. So when the Straw Hats descended to the Blue Sea, they may have landed in the middle of a different route, and immediately, without any problem, Nami's Log Pose pointed to the next island... in that route!
I would know if someone accepts this theory (we will never have any proof, I think) or if there are proofs that I am completely wrong.