Heh. That's a DM with FARRR more time available than I ever have. Sorry, the players are lucky if I have one option prepared a lot of times to be honest. It's why I tend to use modules so much - at least there I have more options available. You've set up a linear scenario - players must travel from A to B and the adventure is at B, as far as they are concerned. As a player, I'm invested in getting to B. That's where the adventure is. That's where we want to go. Everything that detracts from getting to B is mostly pointless side material that I usually have very little patience for.
You've already hooked the players. They WANT to go on this adventure at Point B. They are doing their level best to reach Point B. What's the point in making getting to Point B a trial? We all know we're going to get to Point B. And, the campaign isn't really going to progress until we get to Point B. Typically, everything on the way to Point B is superfluous. That's the whole point of linear adventures.
If anything, what happens between Point A and Point B is an encounter. Just not one rolled on a Random Encounter Table. Don't most pre-made adventures have Random Encounter Tables?
Anyway, you're making a lot of assumptions here. Number one is that having an encounter of any sort is a trial--that
anything that stops you from instantly getting to Point B is a trial. Level Up, for instance, is clearly written by people who like Lord of the Rings, which is almost
entirely about encounters while on the road to destroy the One Ring. It never would have become even remotely famous if we removed all that content and simply teleported from the Shire directly to Mount Doom.
Also, why are you assuming that this is a linear adventure? All you know from this example is that the PCs needed to get from Point A to Point B. But there could also have been Points C, D, and E, and the PCs just chose Point B first. This can very easily be a sandbox game, where the Points are fleshed out. The five ships could have been taken from any number of sources--there are even online
random ship generators. You may not have a lot of time, but I'm sure you have enough time to push a button a couple of times, if you wanted to.
Third, why are you assuming that travel
has to be a trial? Have you only ever had GMs who did travel badly? Go look at Level Up, which really went out of its way to make travel interesting.
Fourth. OK, you mostly run modules. I'm not sure what your point is here. That people who have encounters between major locations in their game are bad GMs? That it's impossible for an adventure that has encounters between major locations to be good?
But, all this is a bit beside the point. The point we were actually talking about is using the character background without it being a real problem. If the players simply said, "Ok, we need to get to X. I'm going to use my sailor background to book passage on a ship."
DM: There are five ships in the port that are going where you want to go.
Player: Is there any real difference between them?
DM: Not that you can tell.
Player: (rolls) I pick ship 3.
Poof. Done. Since it does not matter in the slightest to the players which ship they choose, because they cannot actually know the secret stuff, it's all pretty much a random choice anyway. There's nothing saying you can't add stuff to the journey. That's fair. But, that's also not what's being talked about here.
Except this is incorrect.
@SkidAce said the PCs talked to the NPCs on the ship and then made a choice based on what they learned. By doing so, they learned information about the ships--maybe not the secret spy stuff, but the spy's cover identity.
One of the ships belonged to a merchant lord. If the PCs had chosen their ship, they could have made merchant connections, maybe traded for some interesting equipment, or even tried to steal some stuff.
Any of these things could be important at Point B. But because the ship was owned by a merchant lord, the PCs could also potentially learn about slower travel times due to making more stops, or that the ship was at risk of pirates. Which means it might take longer to get to Point B, but they potentially can get supplies at other stops, or get XP and loot if they're attacked by pirates and win the fight.
One of the ships belonged to a spy. I don't know the spy's cover story, but it's likewise possible that they could have made some sort of connection with them. Depending on the PCs and their classes, they may also have discovered that the captain was a spy and therefore gotten a connection to the ruling class in some way, maybe with good results, maybe with bad ones, depending on what the rulers are like and how the PCs dealt with the spy. There's also the possibility that the spy ship was built to be faster or stronger in some way, making their trip to Point B faster or less risky.
Three of the ships were generic. I'm going to assume that they were small-time traders or fishers. Maybe nothing interesting would have happened if the PCs took one of these boats. Or maybe they would have befriended the captain, who could then be willing to provide room and board at a later time. Especially if the PCs paid really well (let's face it: PCs either refuse to part with a single copper or tip like gold is going out of style.)
Look at all these possibilities--which took me only a couple of minutes to come up with, so don't say that they took "far too much time." Loot, XP, connections, and plot hooks for the future. For what? Spending some time talking and rolling the dice?
Speaking of taking "too much time," that time is often very worthwhile for a GM. For my upcoming game, it will start with a simple "get this thing to this person ASAP" quest. While it's almost a given that the PCs will go via The Tunnels, there's a chance they'll go via The Streets. Since I'm running in Level Up and I wanted to have the PCs to encounter an exploration challenge, I looked up the level- and area-appropriate challenges and saw one for encountering a gang of criminals. I spent a short time thinking about it and from that, was able to imagine a street gang that has a connection to an NPC the players will encounter early on and that has the potential to used as a minor "boss fight"-style event in a couple of levels. This means that even if the PCs go vial The Tunnels, the prep for The Streets won't be in vain.
What's being discussed is the player tries to leverage their background ability, and the DM simply blocks it, vetoes it, or turns it into a disadvantage somehow, all in the name of "role play".
Look at my examples up there. In fact, look at any example I have made in this thread. Show me how any potential disadvantage there might be from rolling the dice or talking outweighs all the potential gains you can get.