Dice are the final arbiter in RPGs, this isn't really a contested fact, it is just how it is. Systems are specified to be diceless, not diced, and that a lone is proof enough of the standard way in which things are found out. Because of this, whenever there is a chance for failure most systems will have you roll dice. However, doing this can really slow down the game. So, how do you keep things moving along then?
The answer is simple, and is up there in the title for this entry. Just do automatic successes. Now, it's not quite as simple as that when you look into it, but on the surface that is exactly it. If you're not rolling dice, then you are just giving them the information they were looking for, or the positive result they wanted, for free. That is where the complex part of this comes in.
When To Call For A Roll?
So, the first thing you should figure out is when you should call for a roll, and when you should just go with the automatic success. The answer is, thankfully, simple. If the action is relevant to the plot, to going forward, or the possibility of failure is particularly important/amusing, then go for it.
If, on the other hand, the action isn't that important to the main idea of what is going on, just give the player whatever it is. Another rule of thumb is that if the character is regularly doing similar things, or would have a harder time failing than passing with a roll, just speed things up by giving it to them.
So, basically, if it isn't important just give it to them. What counts as important? Combat rolls are generally important enough to not be glossed over, as are most dealings with important NPCs. Player versus Player should always use the dice, unless both players are in agreement to another way of doing things.
Oh, on a little P.S., by things the character regularly does I mean things like, if a player says their character does a three mile run every morning (and their stats are where such is believable) making them roll to do a 3 mile run becomes kind of redundant. As does making them roll for a 2 mile run. However, if how fast they can do a 2 mile run could be the difference between life or death for a city, then the dice should come back out.
How Much Do You Give?
So, now you know when you're just going to go diceless, and when you are going to roll, the next thing you need to know is how much of a success is going to be had automatically. For this, you should consult your games skill section. Most will give a 'relative ability' ranking for the different ranks. For instance, in L5R a skill rank of 5 is considered Journeyman (or Professional) level, while a skill of 7 is where Mastery begins, and the highest ranks of 9 and 10 are 'Best in the world' category. Use that, and compare it to what the person is trying to do, in order to figure out how much they can do.
A person with an Acrobatics skill of 10 isn't going to have much trouble performing a simple back handspring, or even things more complex like a string of back handsprings into a double back flip. The same is true for the Doctor with a medicine of 7 having to perform a routine surgery. So, why make them roll when there characters are built to be so exceptional?
Even with lower ranks this is possible. While a character with a rank of 1 in Acrobatics may have problems doing a back handspring, they'd likely have little trouble with more basic things such as hand stands, somersaults, or even dive rolls.
Basically, everything is relative, so look at what the character's skill level is, and compare that to what they actually want to do to decide how much to give them.
I apologize if my thoughts seem a bit broken on this one, but hopefully you can still find things to work with in here. How about the rest of you? Any advice or tips on when to call for rolls, and when to just let the player have it, and how much to let them have?