As the game has developed over many years - and how fortunate we all are that there have been decades of considered development, always presented as options for GMs and players, via the 'house rule' admonition - the once ubiquitous luck saving roll has been replaced more and more with the precision saving roll: strength for this, dexterity for that, speed for some stunt, intelligence to demonstrate awareness, charisma to persuade or resist persuasion.
All very good but don't forget luck. Many situations may not result in a clear cut outcome even when one party makes a particular saving roll. Adding a luck roll into the mix - not always, use it judiciously with an eye to fun and quick-fired play - keeps things fresh and players on their toes.
Maybe the npc might get a lucky break, maybe the monster might do the unexpected or maybe there is a chance of lightning striking twice.
As the Trollgod is so fond of saying, it is better to be lucky than to be good!