Artist's commentary
Hang in There Kogasa-san 2658
You decide character actions using attribute values determined in advance, so if you calculate those values and any correction values, and the dice roll is lower, the results are often failure. That's how it works.
There's also rules that say if you get a crazy-great roll of the dice in this, that's a "Critical" (major success), and a crazy-bad roll is a "Fumble" (massive failure).
There's all sorts of rules for this, like "If you roll 10% or less of the success value, that's a Critical", "If you roll a 100, that's a Fumble", "You can continue to roll and add values as long as you roll a 6", or "You can continue to roll and add values as long as you roll a 1".