That's right, Monica shouldn't change after her service to Philip. But the very idea of the existence of an alternative ending in the basement was born, rather, because of the points introduced by DM, the true mechanism of action of which is still hidden from us. I will not be surprised if it turns out that the essence of their action will be the opposite of what we assume. That is, if Monica scores the fewest points, she returns (as it was intended) to the main storyline in the time frame of the first investors' meeting. But if Monica tries to gain as many points as possible, including extra points whose gain is sometimes accompanied by an increase in her whoremeter indicator points, then perhaps that's what could lead her to an alternate ending. (say, sending her to the Farm).
On the other hand, if gaining 100 points will indeed be possible/necessary to continue playing the main Office route and getting them is not a hidden trap, then Monica could have a pretty extreme remaining 4 days of service (which I really hope for). 7x7=49, even with the extra points still not adding up to more than 63. So, in this case, it should be interesting what sacrifices Monica will have to make to be able to score the remaining ~37 points.