Another angle on the world-then-region or vice versa approach is whether you want to make reality (synthetic reality) drive the makeup of your setting. Example - if you (or some nice random generator) puts a landmass just >there< on a planet, plausible climatology would dictate / suggest "oh, well, the north side would be drier, the south edge more jungle-y". Whereas if you create a detailed bit of continent in your head (I was going to say in a vacuum but we'll let you tell us your impression of the inside of your skull :-) ) it may take some rationalization to put it in a semibelievable place.

I like to let physics, geology, plate tectonics, climate all dictate what would happen to a piece of land just >there<, or what the people in a certain place would have to do for a living given that ocean currents would likely do >thus<, and that volcanoes over >there< would be continually disrupting the vinyards. Pesky, those volcanoes.

NOw, that's all partly due to me LIKING to do the worldbuilding. If you have some old castles that urgently need looting, and a dismal swamp that your players really need to be forced to squish through, you may be impatient with devising a rigorous global setting. In that case, getting enough of the local area set up to permit adventuring is an immediate priority. What's your timeframe? Are there six people in your kitchen, swiftly stripping your fridge, who need to be given something constructive to do Right Now? Or is there six months of slack time you can fill with thinking and drawing?

For me, it's important to know a little about what's over the horizon from the git-go. if the next continent over is half a world away, and mostly desert, noooo sense in writing up the background culture of corsairs and traders shipping jungle-spawned produce and convoys of riceboats. If the next landmass is an easy week's sail, is edged with a zillion islands and rivers, room for a rich tapestry of societies and products, then hey, there can be TEN sets of pirates, privateers, navies, and trade federations, and the effect on the bit of land my players are on now can be profound. I don't have to detail all that stuff over the sea to tell stories locally, but it adds richness if at any point there might be refugees from the typhoons that beset the far coast, or pilgrims passing through from those-islands-to-the-south on their way to the arctic shrines a couple of thousand miles off to the north.

More importantly, you don't have to PUT all those details in the current story / campaign /session ; just having them in your mind is enough to spice-up the milieu. Sooooooo many created worlds fall into the tight-focus, near-is-all-there-is trap. Somebody can refer to "the pilgrim's path" and suddenly there's a nice reason for a route through your current continent from north to south, without your northern and southern kingdoms even LIKING each other. Thinking ahead about other continents tells you there just isn't enough open ocean to the east to allow hurricanes to develop - hence no insurance consortium to insure shipping - hence the big office building your guys are going to loot must be something else, maybe investment bankers or diamond cutters.

I've done well before with a world where a crude overall map existed, and we just detailed nations as somebody wanted to do one.