This is all about the Pacing, Speed, Focus and Duration of the game play.
Roll for Intent [Goal Oriented Rolls] is made for the simpler game play. Things happen in huge sweeping effects. It is simple and direct and does not get into details: things just happen. The player makes a role and does a goal.
Roll for Effect [Task Oriented Rolls]: are for much more complex game play. Only the very specific task the character is doing has any effect. It is complex and will most often take many tasks and many roles to have any effect. The player has to think, plot, plan and use a fair amount of both common sense and game knowledge and mastery.
Say some NPC foes are chasing the PCs through a city:
For Roll for Intent The player just asks the DM "is there something like a barrel full of marbles nearby?". The DM will respond with the "yes, player." Then the Player just makes a Roll and they just escape the NPCs with the idea they "knocked over the barrel of marbles and the NPCs slipped on them". Then the game moves on to the Next Scene.
Roll for Effect is where the PC must find an appropriate thing to block the npcs path, often with no "just ask the DM for one". This player must role play that they are in the city and try to figure out the best place to go. So the player might think of the fish market as a nice place full of wet, slippery fish and head there. Once at the fish market they must look for a good spot, such as a cobblestone narrow alley. Then finally make a roll to knock over a wagon full of fish. The DM here will make save for the NPC, that might or might not be effected. There is very little chance that this single event will let the PCs "just get away", unless they do something quick and clever, often with another roll or two and can do something like get around a corner and cast an illusion. This game moves much slower as the PCs trying to evade the NPCs can take a large amount of time.