Ideal success rate

[LVOD]

I was just wondering: what does everyone think the ideal success rate should be for various rolls? For example, what percentage of your attacks should be hitting, and how often should you make your skill checks and saves?

Obviously certain builds are better at certain things, but I'm asking more from a "fun yet still challenging" standpoint. When you all design encounters, what sort of odds do you stack against your players?

[pwykersotz]

I find a higher chance of success on both sides of the table leads to more interesting things happening. A series of failures is just that, a lack of those interesting ideas manifesting.

Because of this, I prefer a success rate of around 70% for both players and NPC's on their active abilities.

[Kryx]

Success rates for hitting average around 65% according to my DPR of Classes math. Some levels 60, some 65, some 70. With advantage (Barbarian) the average is closer to 85-88%.

65% is the ideal imo

[JackPhoenix]

I was gonna say about 2/3... and it looks like the math already works that way. Lucky guess?

[Foxhound438]

8 on the d20 is usually correct. For a level 1 character, in point buy, this means monsters with 13 AC. Something "harder" will be closer to a 17 or 18 (better armor, target sacrifices attack power for a shield). High difficulty things should be around a 12 on the d20, which the above armor classes work for on level 1-3 characters.

Similar with saving throws, but mostly in the opposite direction. Something easy to land on will need to roll about a 14 on their d20 to succeed, something with a good stat and proficiency will need about an 8. Note that the "needs an 8" is true exactly for cases in which the save you force is on a save that they have stat equal to your casting stat and proficiency equal to yours. For the easy lands, however, some things will have negative stats somewhere, so if you can probe their defenses well enough you should find something extra easy to land on.

[Grod_The_Giant]

I find a higher chance of success on both sides of the table leads to more interesting things happening. A series of failures is just that, a lack of those interesting ideas manifesting.

Because of this, I prefer a success rate of around 70% for both players and NPC's on their active abilities.
I tend to agree-- somewhere around 70-75% for general-purpose heroic tasks is good, enough to count on but not enough to be boring. That goes down to ~50% for "hard" tasks, and up to ~90% for "easy."