HRC-E.B. wrote:Am I correct in understanding that with levers such as the Pro 800 or a Bosco, if one wants, say, 30g in the cup, you essentially have to move the cup from under the group and continue extracting into the drip tray?
In a word, yes.
Isn't there a less messy way of controlling shot volume?
It's not really messy, especially if the (commercial) machine is plumbed-in and -out as designed. And if you want to keep the blonded extraction from going into the drip tray, just substitute a waste cup under the spout when you pull your shot away.
EDIT p.s. Please don't pull the portafilter off before the spring lever has returned to its resting position. Anyone who has done so will have done so exactly once. And talk about a mess!