In the matter of Blackberry, it can be rather important to recall the distinction between the volume of a "Quart" and the volume of a "Gallon," rather than luxuriating in an ability to remember that there are four quarts to one gallon. But should ever a mind remember a recipe as requiring "Ten Gallons of ripe Blackberry" the better plan is to sit quietly and count Tic bites before proceeding, because the odds are that mind has entered the loose-leaf phase.
Then there is the issue of "The Quart." My advice is to never use a "Two
Quart Container" to measure "Quarts of ripe Blackberry." I say this
because sure as onions, somewhere during the process a mighty confusion will
erupt. Paper and pencil is also useful, and there should only ever be one
person in charge of counting. As well, it's worth remembering that as a
general rule recipes measure Blackberry in "Quarts," not in "Gallons." Or in another way, the word "Gallon" and "Blackberry" should never be used in the same sentence.