it simply extends the time
You are able to "work".
It's such an enjoyable and useful process that most everyone chooses to take the booster dose.
It also is a nice safety check, if the person happens to freak out or really doesn't want to continue, they can pass and come back down. But as I Said, in practice no one passes.
It's also not boring or tedious as most therapies can be, it's a lovely place you want to explore.
At those doses, the first few hours would be fairly mild with just a feeling of closeness, openness and comfort. The second dose would push you closer to the ‘oh my god love is everywhere why didn’t I see this before’ feeling.