How many shots do you get at picking a lock in your games? If the DC is 30, and you have a +10 modifier, do you just let them keep trying until they roll a 20?
In our games, you get one shot for each set of circumstances. So circumstances must change for you to try a second time. An example could be you try normally and miss. Then the cleric casts Guidance on you, which is a change in circumstance, and you can try a second time. A third circumstance change could be someone using the aid-another, provided they have proficiency in the skill or tool as well.
Which is all well and good until you have a DM who is confronted by a party that refuses to move on.
Actual experience with this. We had a DM who wanted us to roll to break down doors in a dungeon full of undead and automatons. The monsters did not react to us until we were in a room. We came across a door, rolled, failed.... and then just kept trying. And sure, the DM could have said "you failed once, the door is now completely impassable no matter what you try!" but... that breaks immersion. We had picked a path through this massive dungeon, had zero reason to change our path, and the only thing stopping us was a door where we happened to roll a 3 on the die instead of an 8.
Now, you can proclaim "Bad DM was bad,
I would never call for a check in that circumstance" and sure, fine, neither would I. But if you look at
@Mirrorrorrim 's post.... it sounds like they DID have DMs who did that. Who didn't think through the fact that the party effectively has infinite chances to attempt something, and when the party tried to do what they would logically do (which is try again, like any normal human would) they instead declared the roll had "locked" the objective and refused to let them do it. And that is a terrible way to handle the issue.
Better ways?
1)
The roll indicates effectiveness/time spent: You are in a dungeon attempting to break down a door that in no way is going to end up causing problems if you keep trying for an hour? Then the roll isn't "do you succeed" it is "how do you succeed". Yes, I know, the rules say you don't roll unless there is uncertainty, but by having a roll you can have a high roll let the player feel cool, and the low roll give them some feel for what that failure means. "Total of 5? Okay, you kick the door, and wince as the shock travels up your leg. So you hit with your shoulder. And then kick it again, and after about ten minutes of beating the door the hinges finally give enough that you can pry it out of the wall." That succeeds in getting past the door, but doesn't feel like a success for the character.
2)
The roll changes the circumstances: What if the party is trying to pick the lock on a noble's desk? They logically could try again, but you find that you could increase the drama. Okay, on the failed roll you tell them that they try and get the lock, but it is tricky, and after about five minutes of attempting to get the pins aligned... they hear voices in the hall. Someone is coming. They didn't unlock the desk, they COULD try again, but in trying again they might get caught, so they need to deal with this new problem first. You still failed, but the failure set things up so that you can't just immediately try again WITHOUT setting it up so that you cannot try again. Distract or hide from the person coming in, and you can go back to picking the lock, without having to rely on "your picks broke, jamming the lock, more lockpicking is now impossible." which so many people do.
Either one of these ways isn't "you have only one chance to succeed unless you can convince me otherwise" and also avoids the other massive problem you run into, which is "I try to break the door." "Fail" "Okay, then I'll try" "Fail." "Well, I guess I may as well try too..." and having the entire party rolling until someone gets lucky.
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