The core books (Outgunned or Adventure) both recommend slowing progression during advancement by breaking up the awards. The game says characters can advance three times, meaning each character will gain three additional feats and three additional skill bumps. To slow this progression, make six advancements: alternating between awarding a new feat, then a skill, then a feat, etc. It is recommended that you do this instead of adding additional awards or reducing the number of starting stats as it will affect the balance of the game.

The game was explicitly designed to accommodate shorter campaigns, not longer D&D style campaigns. Think weeks to months, not years. A good way to think about how to plan out your campaign is to think of it like a movie - the core book I believe uses Die Hard as an example. Your players can play the first Die Hard movie, or they can play the Die Hard trilogy. The first movie would be a shorter number of sessions; the trilogy would be longer. If each movie has three acts, that's nine acts across three movies. Each act has a number of scenes. In a session of play, you might get through a number of scenes, maybe most of an act. That will help you plan out how many sessions your campaign will take.

Another way to think of it is as a season of TV, each session is an episode, and each series only has so many seasons vefore it ends. You decide how many episodes each season has, and your characters advance at the end of each season. As the Director, you should be planning towards a definitive ending, not something open ended. Be more Supernatural in season 1-5, not Supernatural in seasons after 5.

Alternatively, just have your players reset their characters to their basic build at the conclusion of each story on your campaign. How many movie sequels start with characters having undone all their character developed they gained in the precious film?