Are there other types of "scenarios", that may be done quickly?
Yes there are. Ideally we should give them other names not to create confusion. For example, you can name "scenario" any fictionalised story about the future (or for that matter the past or the present). These types of scenarios are useful in the context of brainstorming, to try to find wild cards, to foster imagination. However, they will not be as useful as fully detailed scenarios for preparedness. Notably, they will likely not help you be ready across the range of possible futures. They may also not be used for early warning. Thus surprises remain likely.