Well, there's usually another part to the equation: elapsed time. Weather plays the biggest role in determining how much sap will run over a 24 hour period, AND there's a huge difference in the trees themselves.
As an example, we gathered 48 gallons of sap this evening from 55 taps. But, some trees gave up just a cup or so, while others yielded almost 2 gallons. Learning which trees are heavy producers overall is part of being a good sugarmaster.
The other, and arguably more important factor, is learning which trees give the highest quality sap....that with the highest sugar content. Just like ponds, trees are highly variable, and...you guessed it, "it depends".
Roadside trees with huge crowns are favored as being good sap producers....which is one reason you often see big maples along roadways. They very well may have been placed there purposefully, years ago when the road was first established....roadside sap pickup is much easier than trudging through a foot of snow in the sugarbush.
More to point, if you allow a week to collect sap, and boil on the following weekend, under favorable weather conditions, I would say 4-5 trees would be plenty. As the saying goes, "better to have extra than not enough....you can always dump excess sap".
