My sugarbush has 5 different portions, and I recorded the amount of sap and sap per tap on each one. Interesting results. The portions are all a little different from each other but 4 are on the same property, one is 1/2 mile away.
Part 1 - yard trees, 9 taps, small to medium sugar maples. 25 to 50 years old with full crowns, good sun exposure. They were tapped later than most and quit running earlier. Did not produce much sap in the prolonged thaw periods. Zero vacuum. 54 gallons of sap, 6 gallons of sap per tap.
Part 2 - 85 taps, all red maples, small to medium size. Located in woods that I am slowly thinning. Crowns are limited in size. About half on a 3/4" mainline with 5/16 laterals, the other half on two runs of 3/16 tubing. Average vacuum high teens. 698 gallons sap, 8.1 gal per tap
Part 3 - 13 taps, all sugar maples, 3/16 tubing natural vacuum, only about 8-10; of drop. Mostly small size, average diameter maybe 14". Located on field perimeter, along road or woods. Good crowns. Average vacuum around 6-8". 158 gallons of sap, 12.5 gal per tap.
Part 4 - 111 taps, 90% red maples, 10% sugar maples. Most of the sugar maples are mature, possibly 100 years old, with good crowns. Two are enormous trees. The reds are spread out in a woods/swampy area that is being thinned slowly, crowns are limited. Small to medium diameters. Average vacuum 20-24", 6 runs of 3/16 tubing. 1433 gallons sap, 12.9 gal per tap.
Part 5 - 45 taps, all mature sugar maples along a roadside, probably 100 years old. Medium to large size. Two runs of 3/16" tubing on opposite sides of the road, natural vacuum. Drop about 20', average vacuum about 8-10". 850 gallons of sap, 18.9 gal per tap. Wish all of mine were like this and on high vacuum....
So in my case, looks like the way to get more sap is to find better trees! Or hope that thinning helps, eventually. I did not get more sap on trees with highest vacuum, I got more sap on the bigger trees. I made 56 gallons of syrup from the 3100 gallons of sap so sugar content wasn't great. I'm thinking the biggest factor on syrup yield is tree and crown size not red vs. sugar maples. Weather too maybe.
Dave