Adding to this: I don't think that AW, when it refers to countdown clocks for threats, envisages them being player-facing. I think that they're part of the GM's prep, to establish what the "offscreen" badnesses/threats are and what they do. From p 143:
A countdown clock is a reminder to you as MC that your threats have impulse, direction, plans, intentions, the will to sustain action and to respond coherently to others’.
When you create a threat, if you have a vision of its future, give it a countdown clock. You can also add countdown clocks to threats you’ve already created.
Around the clock, note some things that’ll happen:
• Before 9:00, that thing’s coming, but preventable. What are the clues? What are the triggers? What are the steps?
• Between 9:00 and 12:00, that thing is inevitable, but there’s still time to brace for impact. What signifies it?
• At 12:00, the threat gets its full, active expression. What is it?
As you play, advance the clocks, each at their own pace, by marking their segments.
Countdown clocks are both descriptive and prescriptive. Descriptive: when something you’ve listed happens, advance the clock to that point. Prescriptive: when you advance the clock otherwise, it causes the things you’ve listed. Furthermore, countdown clocks can be derailed: when something happens that changes circumstances so that the countdown no longer makes sense, just scribble it out.
On the other hand, a countdown clock created in order to "disclaim decision-making" (p 115) seems like it might sometimes, even often, be player-facing:
Say that there’s an NPC whose life the players have come to care about, for instance, and you don’t feel right about just deciding
when and whether to kill her off: . . .
Just sketch a quick countdown clock. Mark 9:00 with “she gets hurt,” 12:00 with “she dies.” Tick it up every time she goes into danger, and jump to 9:00 if she’s in the line of fire. This leaves it in your hands, but gives you a considered and concrete plan, instead of leaving it to your whim.
I don't see that AW mandates a uniform practice here.
Now, I can't comment on BitD, which is a different game.