I've heard different things from different folks, but I was wondering: in Story Mode, do most GMs allow characters to go more than one step in Reckless or Conservative? At the moment I allow whatever they have but I've heard some GMs only allow one step either way until Encounter Mode. I haven't found specifics in the book so I was curious what others are doing.

I have a PC one deep in their dominant stance whether they want to be or not, unless there are clear RP reasons they should be somewhere else. But, if it fits the story and the RP then they'll have whatever stance feels right.

the FAQ available for download mentions stance during story mode. see the section Stances: Neutral Stance Clarification

basically it says that if the GM is agreeable and there is a story based or narrative reason then the stance can be adjusted as necessary. there is no mention of a restriction to how far into a stance you could be.

I allow a single stance die if the player can explain how he's conservative or reckless.

same as Gallows here, assuming we're "true story mode" such as a single shopping roll, recognize that guy coming out of tavern etc. roll.

I generally allow 1 step in as long as it is roleplayed out. If you want to go further in for a scene, you can spend stress.

Since the Rally Phase adjusts stance one step in the direction of neutral, we decided that we basically play in neutral mode and the players have to adjust their stance if they want it otherwise. So in Story Mode they have to narrate why they change stances and how. So for example how they try to calm down to reason with an npc or such.