As a Doom Master, do you enable the PCs to stack their unspent Fortune Point from session to session - up to a limit of 5 - in the course of a campaign ?
No, they reset to the baseline at the start of the session (as per page 276). Fortune Points are quite powerful but when the players know they reset at the start of the session they are far, far more liable to spend them during a session which makes their characters more epic.
Everything resets at the start of a new session.
- Fortune points to the individual character’s refresh.
- Group Momentum pool to zero.
- Doom to the sum of the characters’ Fortune points.
I do reward Fortune points in the course of a session. If the players don’t spend them, they are gone.
There is a strong incentive to spend Fortune, not only for Skill tests and additional Standard Actions without penalty, but to introduce new details to a scene, introduce a new contact, a new relationship, etc.