I don't think so.
What's "narrative convenience"? To me, it would be "changing the setting in a way that it pleases me more". And I can't see why that's a bad thing. True, Dresden says that teleporting is not really doable, but to heck with that. I want to play Dresden Files WITH teleportation. What's wrong with that? The book even says, if you don't like something, change it. It talks about killing Harry off in Storm Front, for crying out loud. If that's ok, teleporting really shouldn't be a big deal.
Second, "mechanical convenience". And yes, it is absolutely ok to handwave certain things. I look at it like things from novels or movies. Indiana Jones, for example. All the travel parts are Indy sitting in a plane with a map overlaid and the big red marker following his path. You don't see him drive to the airport, buy a ticket, wait to board, board, get a drink, get off the plain, get his baggage, and so forth. You could roll for all of that in a game as well, but it would get kind of boring after a while. And I see the same thing applying for teleporting as well. If you are just using it to get from A to B, without there being anything really important about it, why roll at all? I wouldn't make you roll drive to see if you can get to the other side of the city to the next scene, it doesn't matter if it takes 20 minutes or half a second, it's just where the story continues. If you need to get somewhere in time, however, I would make you roll on both, to see if you get there in time (by getting 15 shifts in 3 exchanges, for example).
It just isn't fun to calculate the difficulty for about half an hour, roll and the situation is forgotten 3 seconds later.
Or lets look at it this way: If you can teleport, the city you are playing in can be a whole lot bigger. Instead of your favorite restaurant being two blocks away, it's two states away. That's about all that's really to it. If you roll to drive down town or teleport across the country to get to the bad guys, dramatically, it is pretty much the same thing, and that's what counts. Don't make it any more complex than it has to be.
Or even another example. Let's say I'm really good at this nevernever teleporting stuff. Now I'm fighting someone and he tries to disarm me. I can successfully defend against him, so I can keep my sword.
OR, because I think it is much cooler that way, I say he slapped away my sword, but I instantly move my hand to the left, opening a rift to grab my sword as it whirls through the air. In the end, the result is the same: I still have my weapon. But, at least to me, the portal way is a really cool way to narrate this. It doesn't matter how high you would have to roll to open a portal, it's just part of this action and only flavor. Of course, I could get a stunt that let's me do maneuvers like that with lore or something similar, and get even more cool effects out of it, but that's another discussion entirely.
It's all about what I make of it, what's the impact on the story? If it doesn't have any impact, why roll? If it has a minor impact, why require a huge roll? If it has a plot point impact, any roll seems rather weak, so just treat it as a plot point.