Whenever I ask players to make a roll I have the following two things into consideration:
- Would it be dramatic for the players to fail at this point in time?
- Is this a place where the failure or success of the players can lead to a branch or some other consequence in the story?
A practical example:
The current plot requires that two characters sneak into a place to retrieve something. This is not a maximum security facility and even if the characters get into trouble, they could easily overpower any attempt to stop them (either to Disciplines, Arcana, Contracts, whatever). However, they have a good reason not to get caught: another supernatural considers itself the owner of this territory and they don't want to make enemies because they might need some help from them or one of their allies in the future.
I have the players make an extended Dexterity + Stealth to sneak in unnoticed, but they fail. I give them some choices:
- Spend some Mana/Vitae/Aether/whatever to force their way through (and potentially risk Paradox/Cover or something else as well).
- Have the other supernatural eventually learn about their imprudence.
- Give up on their mission and try a different approach next time, which might require a different kind of roll to get what they want.
As you see, the roll is dramatic and failure provides new options for the story, which is the perfect situation where some random chance should be involved.
Edit: Interestingly, the above example is from a real game and the players chose a dramatic failure to get a beat. They got stuck with two negative consequences.
Another edit, to give an example of a social situation where rolls and other mechanics are used, this is also from that same play through, it was Blood & Smoke:
The characters want to setup a trap for the kindred that governs an affluent territory and convince him to give it up. Of course, there is no way this can be done in a amicable fashion but combat is out of the question to prevent sheriff intervention.
They decide to do some investigation and target the right hand man of the territory holder. Some of their investigation rolls (calling friends, contacts, checking the books, asking witnesses) are a success and they discover that this right hand man has a grudge against his boss, but don't know more yet (they didn't get enough successes for that). Judging it to be enough knowledge (they don't want to waste more time investigating and risking rolls), they confront him and ask him for a deal.
Here we used the Door system. The target has 4 doors to be opened if they want to have his help in setting a trap for the boss. They prepare a nice environment for the man (including some feeding opportunities) and treat him with proper etiquette (throwing in some Socialize rolls to see if they know what etiquette is proper). We agree to a Good first impression, so its gonna take them 1 day per roll. Once everything is in place, the seductive member of the group brings up his relationship with the boss with a Manipulation + Persuasion roll. A success means one door comes down, and the man spits out some information on the grudge, confirming their investigations.
Another one of the members at the table uses a Merit (in this case Friends in High Places) to make a call and ask for this guy to get a promotion just in case something happens to his boss. The merit allows to immediately break another two doors. The characters basically convince him that they are on his side. Help us and we help you. The man tells him that he has to think through all this situation, after all he is going to betray his boss and could end with him dead if something goes wrong.
At last, they get a call from him, "I never liked working for this guy. There is another ally of him that spoke against me in front of the prince and got me demoted, forcing me to be his servant. I know this other ally is trying to embrace one of her favorite followers and I want to get even. Get the mortal out of the equation and help me look better than the boss again (which was already covered by the Merit used before), and I will set up any kind of trap that you want."
So to break the last door, they have to find a mortal and either kill him or scare him away, not hard. They have to make several rolls through this side-quest but the very last one is going to be the one that counts towards fulfilling the Social maneuver. They ended up kidnapping the guy and rolling Presence + Intimidation (aided with some Majesty) to break his will. They somehow FAILED. The puny mortal was way more strong willed than they thought.
Instead of simply telling them to try again or halting the story there (although we did take a few moments to laugh at the situation), I gave them an option: this guy has seen through the masquerade and knows way too much, he either has to die or be embraced. One of the characters was a Lancea et Sanctum and he convinced the others that the guy should decide by himself. We made no rolls for the embrace and staking scene that followed.