Oh no! Please read the following carefully!
You are going about casing all wrong.
Stop thinking about set times, set rules, and some of these weird things you feel like you should and shouldn't do.
First, your framework needs to be a clear plan for how you would answer the question. Nothing else, nothing more. So, "you just have to write down the first layer, and speed through the case to find the lead that takes you to the conclusion" and "I just say I want to look at these 4 buckets, explain a little bit the logic why, and then I just go? "is HORRIBLE ADVICE.
Your framework is your structure for approaching the problem. It consits of a few main areas you'd like to look at. Inherent in your framework is a view that "If I answer A, B, and C, then we have an answer"
So, for market entry:
1) If the market is big, and it's growing, then we still want to considering entering
2) If #1 = yes, then let's see if it's attractive...can we win there? Is our product good/better than our competition's? Etc. If yes, let's definitely consider entering.
3) If #1 and #2 = yes, then, when we do enter, are we sure we can win? I.e. do we have the right plans. Will implementation actually pan out? Do we have the expertise, capital, etc.? In other words, if #2 is the thearectical, #3 is the reality.
Then, your summary becomes "I believe we should enter the market, if we can prove it's a good market, the it's attractive to us specifically, and that we will win it".
^Now this is a framework/hypothesis
Some other guidance
#1 Frameworks are a guide and are meant to be adjusted
So, you should absolutely be prepared to either enter a new piece of your framework or change your framework altogether as new information comes in. How do you handle this?
Well, first, you can really just articulate what you're doing. You can say "Oh, interesting, so if looks like we have some information on y. I don't want to forget about x, but let's see what y brings us first. Ok, looks like it's about..." Then, when you've "finished" with y, you can check to see if there's any info on x. If there isn't, move to z :)
Second, you can re-summarize/iterate where you are. This is especially useful if you have the change the entire framework. Say "Ok, so it looks like now we actually need to look a 3 key things to solve this"
#2 You can absolutely have "no buckets" when brainstorming...if needed
This is really a judgement call and depends on the type of brainstorming. In terms of selling strategies, I agree with you, this can really fundamentally be a list. However, try to bucket. For example, you could bucket selling strategies as 1) Those that bring in new customers and 2) Those that increase the value of existing customers. Alternatively, it could be 1) Increase basket size per visit 2) Increase visits per customer 3) Increase # customers
Read these 2 Q&As for some great context + discussion: