That doesn't correspond to SWIM's tests in a Soxhlet using boiling water. Extracting for 48 hours gives nearly double the yield of extracting for 24 hours. But this relates to Soxhlet extraction, and not normal boiling in a pot. In a Soxhlet, the plant matter is never exposed to boiling water, just hot water. But the extracted liquid is boiled continuously for as long as the Soxhlet is run. Running for 1 weak gives slightly better yields than 48 hours, but isn't worth it. It just goes to show that the alkaloids can withstand being in boiling water for 1 weak with no loss of yield.