For what it's worth, you could watch how quickly the confidence intervals converge as you sample the data, to see if it's worth continuing or if the variance is too high and whether you'd have to check thousands of pages by hand:

   from scipy.stats import binomtest
   chance_of_dead_page = binomtest(landing_page_counter["dead"], landing_page_counter["total"]).proportion_ci(confidence_level=0.90)
   print(f'Chance of a dead but existing landing page (90% Confidence Interval):{chance_of_dead_page.low * 100:.2f}% to {chance_of_dead_page.high * 100:.2f}%')