I really wanted to give a nice elaborated answer to this question but I don't have enough time right now. So here's my short, quick answer:
From the perspective of Philosophy of Language, there's a lot to say about your question.
Firstly, in Bad Language, Herman Cappelen offers an entire chapter on "The Speech Act of Consent" (chapter 11). This text explores definitions of consent (first introduced as "a speech act whereby we agree that something is true", but then gradually expanded in depth and scope), walks through many examples and considers how it works. There are a few examples of sexual activity policies in universities (in the context of preventing sexual assault), where your specific question is partially addressed:
Consent to some sexual acts does not constitute consent to others, nor
does past consent to a given act constitute present or future consent.
Consent must be ongoing throughout a sexual encounter and can be
revoked at any time.
Cappelen, Herman; Dever, Josh. Bad Language (Contemporary
Introductions to Philosophy of Language) (p. 184). OUP Oxford. Kindle
Then various problems are explored.
- What counts as an individual sexual act that requires consent renewal?
- Can deception undermine consent?
- How does implicit consent work?
- When is explicit consent required?
- The difference between tacit consent and silencing (or "silencing" vs. "being silent")
And toward the end the chapter describes the inherent complexities in the act of consent, and its dynamic nature.
Secondly, in Sexual Solipsism, Rae Langton discusses the complex topic of sexual violence and its connection to consent and how pornography can shape human behavior related to it (in chapter 1.2. "Pornography Silences")...
Example (5): Refusal. Consider the utterance 'no'. We all know how to do things with this word. We use it, typically, to disagree, to refuse, or to prohibit. In sexual contexts a woman sometimes uses it to refuse sex, to prohibit further sexual advances. However, in sexual contexts something odd happens. Sometimes a woman tries to use the 'no' locution to refuse sex, and it does not work. It does not work for the twenty percent of undergraduate women who report that they have been date raped. It does not work for the twenty-five percent of final-year schoolgirls who report that they have been sexually forced." Saying `no' sometimes doesn't work, but there are two ways in which it can fail to work. Sometimes the woman's hearer recognizes the action she performs: i.e., he recognizes that she is refusing. Uptake is secured. In saying 'no', she really does refuse.
By saying 'no', she intends to prevent her hearer from continuing his advances. But the hearer goes ahead and forces sex on the woman. She prohibits, but he fails to obey. She fails to achieve the goal of her refusal. Her refusal is frustrated. 'Perlocutionary frustration' is too meek and academic a label for what is simple rape. Sometimes, though, there is the different phenomenon of illocutionary disablement. Sometimes 'no', when spoken by a woman, does not count as the act of refusal. The hearer fails to recognize the utterance as a refusal; uptake is not secured. In saying 'no' she may well intend to refuse. By saying `no' she intends to prevent sex, but she is far from doing as she intends. Since illocutionary force depends, in part, on uptake being secured, the woman fails to refuse. She is in the position of the actor in Davidson's story, silenced as surely as the actor is silenced. He shouts 'Fire!' He performs the appropriate locutionary act. He means what he says. He intends to warn. He tries to warn. But what he says misfires. Something about him, something about the role he occupies, prevents him from warning the audience. She says 'no'. She performs the appropriate locutionary act. She means what she says. She intends to refuse. She tries to refuse. But what she says misfires. Something about her, something about the role she occupies, prevents her from voicing refusal. Refusal-in that context-has become unspeakable for her. In this case refusal is not simply frustrated but disabled.
Rae Langton. Sexual Solipsism: Philosophical Essays on Pornography and Objectification (Kindle Locations 705-718). Kindle Edition.
Anyway, I apologize for the long quotes and the shallow elaboration, but as I said, I don't have much time at the moment. I may edit this answer and offer more elaborated insights later on.
But just to quickly summarize: I think there is immense value in conceptualizing consent as a Speech Act, with all the implications this entails (e.g. discerning locutionary, illocutionary and perlocutionary aspects), and I recommend thinking deeply about what is it that matters when one gives consent? And from that perspective, are such important aspects hindered when various situations arise? (late consent, revoked consent, misunderstandings about consent, tacit consent, silenced refusal, etc.)
Additional readings I'd recommend to better grasp the subject of consent (or rather, to better understand human intentions and actions, as a foundation for the understanding of consent) would be:
Derek Antony Parfit... was a British philosopher who specialised in personal identity, rationality, and ethics. He is widely considered one of the most important and influential moral philosophers of the late 20th and early 21st centuries
Her monograph Intention (1957) was described by Donald Davidson as "the most important treatment of action since Aristotle."