It is set to off now. I can press/hold the manual button for it, but I don't anymore. But that is mainly because of the roasts I prefer. I did spend quite a bit of time a year or more ago when I coined the CNAS acronym, using the BDB preinfusion in a 'Certainly Not A Slayer' emulation. I've not done the hot water switch mod so that one can pressure profile during the pull, though.
For me, it seemed like the preinfusion added value when using lighter, denser third wave roasts which, it turns out, are just not my thing. I was going to say not my cup of tea, but some of those roasts taste more like tea than coffee to me
Every once in a while on a whim I'll try a preinfusion-to-first-drip, but I haven't noticed anything significantly different in the cup.
Maybe if I can ever get consistent at latte' art, I reapply myself to preinfusion/pressure profiling experimentation.