It depends on the person, but trips like that may take a fuck ton, multiple times. I have heard of multi-day trips before that were caused because of doses higher than 15-20g. Napkin math puts that in the 150mg-200mg range of actual psilocybin. Regardless, it would be processed out of the body in about 24hrs. I am personally skeptical of multi-day trips, but they probably do happen.

There are plenty of caveats, so give me time to explain.

The effects on the brain after a trip can go into the multi-day range. For my trips I take between 3-3.5g depending on how I feel. I'll peak about an hour after and trip fairly hard for 3-5 hours. (It's also to be noted that the shrooms I grow are generally on the mid-high end of potency.) The afterglow, or come-down, takes another 4 hours or so and I'll still see a literal glow around things or mild visuals. This is where my super-social personality comes out, and I love that part. If the night is going to be long, I'll probably end up eating in in upwards of 10g more through the evening just to maintain very long come-down. Peaking again is possible, but it's unlikely.

For a couple of days after, I still feel something. It's more of a mental clarity or an alternate perspective on things. It's hard to describe.

Edit: It's speculated to act similar to a SSRI antidepressant in that regard. It reduces serotonin uptake for those receptors and increases serotonin availability in other parts of the brain.

What is happening, and from what I understand, is that psilocybin is an extreme 5-HT2A agonist. It saturates those receptors and tends to stick around for a bit when it does. This results in rapid tolerance to psilocybin since there won't be any receptors left for it to "agonize". It can take a week or more of abstinence to get the same level of trip with a similar dose.

You can game your body for a little bit, but you have to double-down on the dose. If you tripped yesterday off of 5g, you would need to eat 10g today and 20g the next and so on. For a 48hr trip, assuming his reaction is "normal" (if there is such a thing) he would of had to double down every 4-6 hours or so. Either way, it's a lot of shrooms to eat and your stomach will absolutely punish you for it.

There is a little science behind this, but the experience and dosages are extremely variable from person to person.

I am not a doctor or a scientist. I read a fuck-ton on this subject from real studies from reputable universities. Search YouTube for some of the more recent lectures coming out of U.C. Davis if you don't like to read. Still, that doesn't make me an expert and I only truly know my own tolerance and experiences.

You will inevitably stumble across Paul Stamets as well. He literally wrote most of the first books about psilocybin and mushroom cultivation. While he is a knowledgeable and almost inspirational person, he does lean heavily into subjective experience. That's fair, but it is what it is and he does mention it himself. And he owns a medical mushroom company. However, I respect that he doesn't hide his own bias.

This subject is extremely understudied at the moment.