Choose the model before reading the percentage
A fixed-rate scenario uses 1 - (1 - p)^n. A progressive scenario multiplies the failure probability from each conditional rate. These are different assumptions: adding an increase because a player has gone dry will overstate the result unless the target actually has that mechanic.
Do not reuse one Exotic's rules for another
Bungie has described bad-luck protection for Eyes of Tomorrow: qualifying weekly account clears build protection and the design can eventually guarantee the reward. The same publication does not provide a reusable base percentage or increment, and it does not establish that every raid Exotic follows that system. That is why this calculator does not preload a Destiny-wide curve.
Source: Bungie, “This Week at Bungie – 3/18/2021”.
Count attempts that could award the target
A completion total is not automatically an eligible-attempt total. Check the current activity tooltip, rotation, character state, checkpoint, and reward rules. When eligibility is uncertain, keep that clear outside the confirmed count instead of forcing it into the model.
Interpret the output as conditional
“64% under a 5% fixed-rate scenario” means the entered assumptions produce that number. It does not mean Bungie published 5%, that your private account currently has 64%, or that another clear is due. The no-drop percentage remains possible on every non-guaranteed scenario.
Related guide
Use the Destiny 2 eligible-attempt guide to build a source note and clear log before choosing inputs.