limelight it’s a good question if you are doing pre-infusion. With something like a 3+3 pre infusion (3s line pressure, 3s rest), you may end up grinding a little coarser than optimal if you are targeting ~30s total. Would love to get others thoughts on pre-infusion as I usually target a few seconds longer when doing it.
Pre infusion makes the shot run significantly faster so if you were arbitrarily targeting a shot time you’d have to grind finer compared to running the shot *‘without’ the pre-infusion.
*You can’t really run without pre-infusion because it happens as the puck is wet and saturated, which obviously always has to happen regardless of pressure or whether or not the pump is running.
To expand on my early post simply as “Never”. My machine has a built in shot timer that starts when I flip the switch. I use it for no other reason than to assess consistency from one shot to the next. It makes no difference when you start the timer so long as you do it consistently. The majority of the time I pay absolutely no attention to it whatsoever. I’m more focused on the flow rate than anything, and ofc the target weight. Yes, the time can be used to determine average flow rate, but that isn’t particularly useful at all. You’re better off watching the shot and the scales and stopping it when you want so you can track flow rate and weight. If you pull two shots, one for a 1:2.5 in 30 seconds with a flow rate that starts slow and steadily increases, and another 1:2.5 in 30 seconds with a flow rate that takes longer for the first drip and rapidly increases, you’ll have two very different shots.
I wouldn’t personally alter the grind setting or dose because a shot takes 25 seconds or 50 seconds, but I may let it run longer or cut it earlier depending on the flow rate regardless of weight out.