For 17-32 players the standard is 6 Swiss rounds. With twenty players, five rounds is already a bit short (too many people on equal points), and six reliably reveals both the winner and the whole podium.
It's exactly at this size that doing it by hand gets truly hard: 20 people, 6 rounds means pairing ten pairs each round with the match history and colors in mind. The bot does it instantly and without errors.
On blitz 10+0 a round is about 20-25 minutes (10 games in parallel), six rounds about 2-2.5 hours. For a school competition day that fits a few lessons or one big block. You need 10 boards.
For a group of 20 the live table is especially useful: put it on a screen or board after each round. Kids follow their place, and the bot recomputes points and Buchholz automatically - nobody gets confused about who's where.
A scenario: a grade or big class, 20 players, blitz 10+0, 6 rounds, certificates for the top places. The teacher creates the tournament in the bot @vibechessbot, enters kids as guests by name (no phones needed), runs /start_tournament and /next_round between rounds. The teacher's detailed guide is in the tournament at school article.
Six Swiss rounds. For a field of 17-32 that's standard: five is too few (many players on equal points), and six reliably decides the winner and the whole podium.
On blitz 10+0 about 2-2.5 hours (six rounds of 20-25 minutes). All games in a round run in parallel, so time depends on the control, not the number of people.
It's hard: 20 people and 6 rounds means pairing ten pairs each round with match history and colors, plus computing Buchholz for everyone. The bot does it instantly, so automation really pays off at this size.
Ten - one per each of the 10 parallel games. With fewer, some players wait their turn and the tournament stretches.
Put the bot's live table on a screen or board after each round. Points and the Buchholz coefficient are recomputed automatically, so the standings are always current.
The bot is constantly improved based on real tournaments. If you need a feature that isn't there yet, message the developers right inside the bot with the /support command. Many features appeared exactly because organizers asked for them, and useful ideas get added quickly.
A smaller group - 16-player tournament. A bigger one - 30+ player tournament. About the round count - how many rounds in the Swiss. At school - tournament at school.