There are two questions here, it seems: What should count as consent in practice, and what should count as consent in policy?
In practice, I think that if someone gives overarching consent like that, it comes with accepting that the partner might do something he/she doesn’t like. But if the person trusts the partner with that kind of leeway, I assume it means he/she feels comfortable telling the partner to stop and believes that the partner will comply. In turn, if the partner agrees to be spontaneous, he/she is trusting that the partner who asked won’t turn on them and report them if they start to do something unwanted. If both parties trust each other to that extent, I think those kinds of consent are fine as long as both parties are coherent enough and comfortable enough to withdraw consent.
Do I think these phrases should legally be protected? If someone could claim about an accuser, that he/she gave prior consent to be spontaneous and he/she was fully capable of withdrawing consent during, and he/she was actively, “enthusiastically” participating (which isn’t just “responding” to the sex), then it shouldn’t be considered rape or assault. But if someone accuses you of rape and #2 and/or #3 didn’t hold, then #1 isn’t enough. Like I said, people can make their own perfectly legitimate rules about consent but the law can’t cover all of them; that’s why it has to capture the essence of consent enough that people can say, “He/she did this, and these criteria are fulfilled, so now I have consent.”
There are people who want to dominate or have an assertive partner, and such people don’t see anything wrong with someone doing certain things without explicit consent. And there are people who first and foremost want their bodily autonomy respected or want to know that they’re respecting the other person’s bodily autonomy. Such people would see someone doing anything without explicit consent as assault. So it’s fine if you prefer women of the Type 1 persuasion, since that’s the perspective you also share. But it’s always better to assume Type 2, since turning someone off/being turned off is better than assaulting/being assaulted.