In the revolution days lawyers used only two or three books to practice law. Definitly a Bible and a Law Dictionary. The others were most likely a copy with the few laws of the time.
Now we have 12 linear feet of new case law every year.
America did inherit English common law principles which far exceeded the statutes in existence. I suppose you're probably right, but any lawyer with access to prior decisions would carry the day.
Much more than that, if you count all jurisdictions.
On the other hand, back in the old days, when lawyers only had Story/Storey on the Constitution and Black's Common Law and a book on equity and a book on pleading, they winged it a lot. Not just the lawyers, but the judges. They made up stuff as they went along.
Lots of weird opinions, but you probably don't study old case law much, is my guess.