For discovery and Module C, I'm all about that low modality life. My reason for this is, you are making a statement about a concept (discovery, people and landscapes, or people and politics). And then you're saying that the statement is true according to the texts. You're not saying the statement is true of life in general. You can't truthfully say, "Discoveries are intensely meaningful" because sometimes they simply aren't. And, you might have one text that proves that statement, and another that proves a variation. So, I prefer the lower modality because it means you have scope for a "discussion" style of argument where you can flick between the texts and look at how they gel with the question.
As for Module A, I didn't intentionally approach it in a high modality way, but I was speaking of fact. When you discuss context, you are speaking factually. So, for Module A it is most likely that you'll sit in a higher modality seat because you're making connections between two periods and two texts, not so much making a comment on a concept of humanity like AOS and Mod C.
Mod B again is different. You can structure this essay a bunch of ways. I tended to avoid the first person narrator and opt for the approach of, "A contemporary audience may relate to the work of..." So this automatically falls into a low modality. But if you are espousing a first person narrator, then it might be more natural to speak in the higher modality.
Essentially, I think that Mod C and AOS are most suited to a low modality. Mod A is most suited to a higher modality. Mod B can be a combination. Neither are incorrect or correct, but rather, what suits your purpose? What conveys your point the strongest? In what tone do you sound most articulate? Asking these questions is how I decided what modality to use for each essay 
I'll disagree with Elyse on this one, and let me explain why

I agree that AoS is about making a specific statement in light of your study of the texts. It won't be true in all situations. However, I still think that your ideas need to be stated
emphatically. I mean, phrases such as "______ may induce _______." are definitely cool, but I still prefer high modality language for all my essays. In my opinion, it just sounds more sure. Using low modality excessively can come across as unconfident, again, in my opinion

if you do want to use it, walk the line carefully and make sure you still come across as confident as what you are writing.
That said, whichever you choose,
definitely employ high modality language in your analysis. Don't do this:
The composer's use of powerful visual imagery may invoke sympathy in responders.That
may kills your momentum dead, because it shows that you aren't sure of the arguments you are making.
So, while I agree that it's a bit of a matter of preference for conceptual statements about discovery (although I still always prefer high modality), definitely employ high modality in your analysis. While you might want room to move conceptually, don't leave room to move analytically
