No problem with that. But compare these two experiments:

  for i in range 623:
    data.add_result()
  s = calculate_significance(data)
  if s > 0.95:
    publish()

  for i in range 623:
    data.add_result()
    s = calculate_significance(data)
    if s > 0.95:
      publish()
      break

The second one gives you many more chances to succeed, which must result in your confidence in the answer going down.