Indeed, the number of "observations" (choice tasks) differs by person.
BYO: each attribute included in the BYO is formatted as a separate choice task.
Screener Section: Each near-neighbor card generated is counted as a choice task (binary choice versus the "None" threshold). PLUS, any time an Unacceptable or Must Have is indicated by the respondent, ACBC looks ahead to see if any already generated cards that have not been answered yet would violate the screening rule. If so, responses to those cards are inferred (become choice tasks, where the "None" alternative is chosen) and new cards are generated to replace those inferred answer cards.
Choice Tournament: Depending on how many cards were marked as "a possibility" in the Screener section and depending on whether you have formatted the Choice Tournament to be 2 concepts per task or 3 concepts per task and depending on whether you chose to include your BYO card in the choice tournament, enough choice tasks are asked to complete the round-robin tournament and identify the overall winning card.