Agreed! I've found that skipping PI or ramping up pressure too quickly almost always leads to a worse extraction. I typically PI at 2bar for 10s and I get very even coverage of the shower screen and maybe 2 drips into the cup.

My understanding of why the resistance seems lessened by a gentle PI is this: If you ramp up too quickly, the pressure creates a "seal" between the water and the coffee that resists flow. You can easily choke a shot dialed in for PI if you rush through it. Conversely, a gentle PI allows the water to permeate the entire puck before compression starts to seal off many of the water pathways. If there are many open pathways, the likelihood of one becoming a large channel is lessened significantly. And as we know fewer channels means a more even extraction means better coffee.

I've owned the Robot for a little less than a year now, and although I deployed many different methods, I could never really fine tune things to get the taste to something ideal. Lately, I've discovered a method of brewing on the Robot that have yielded the most fantastic results I've ever had, and I'm finally content with what I get in my morning cup.

It involves a paper filter. No, not the default round ones that come with the Robot. With the pandemic I had trouble getting my hands on them. So I used someone's advice in this thread to go to the supermarket and just buy any generic #4 coffee filter and cut them to shape using the tamper as a guide. I tried this at first, but I didn't really notice much improvement in my subjective taste.

Like a lot of anecdotal reports in this thread, my extractions almost always start at the edge, so I've always been suspicious of side channeling as the source of my woes. I believe my side channeling was so severe that, it completely avoids the middle puck for most of the extraction, running only against a side wall. I've spent months trying different WDT methods, different grinds, different dose, I could never solve it.

One day I had the idea to cut the paper filter into an oversized circle (several millimeters in diameter wider) so that when I place it under the screen (above the tamped puck), and push down with my thumb with some effort, there is noticeable paper filter sticking up and out from below the screen, ideally around the entire circumference of the screen. The idea is that, with paper squeezed between the basket wall and screen edge, securing around the entire perimeter, pressurized water is less likely to escape these paths of least resistance. It's a bit tricky to get into place, which just speaks volumes about how precise the engineering is. Nevertheless, when all of this is in place and I brew with no other variables changed, I get dramatically better results, the type that I'd always hoped for when I decided to make espresso at home.

Anyway, thanks for coming to my ted talk. Anyone who has had difficulty with their Robot, especially if side channeling is suspect, I recommend giving my method a shot! It's cheap and only adds several seconds to my morning ritual. I cut these circles in bulk while I'm watching the NBA or something. I'm not sure why it is that I need to do this to use my Robot as it was intended out of the box, but I'm glad I found an easy fix. I thought my screen would be a bit warped, thus side channeling, but it's perfectly aligned as if new from visual inspection.