Explores the best format for finals day …

Firstly, there's no single best format. It depends both on what you're trying to achieve, and the spread of abilities among the teams.
If they are all very well matched, the best format is quite different to where there's a wide spread of abilities and many 'near walkover' races.

However, there are some general principles.

In no particular order:-

• The winner should deserve to win. A good test is that everyone, including the runner-up, feels the winner was the best on the day.[1]
• One race eliminators rely too much on luck. If running short of time it's far better to abandon quarter finals and have full semis and finals than to compromise all the knockout rounds.
• Everyone wants at least some sailing on the last day.
• Where the gulf between bottom and top is bridgeable, it's nice if everyone feels they could win. Where the gulf is unbridgeable, minnows learn most (and have more fun) sailing other minnows, not from trailing round after the hot shots.
• Any format which only uses - for example - one set of boats when two are available wastes sailing time for someone.
• Regional qualifiers often send 2 teams on to the national final. Any format which sends the best 2 teams succeeds. Any notion of a single winner and a runner up at such events is meaningless, especially if it cuts across the 'worthy winners then most fun for the greatest number' aim.

[More to follow]

Here's an example.

It came from a 7 team event. After 2 days sailing (2 full round robins), 3 teams seemed capable of winning; 2 had little hope.

It is presented as one (of many) ways to proceed. It could certainly be used as a pro-forma, or adapted as is. But I hope it will additionally trigger thought and experimentation.

[More to follow]

Finally, it's the Race Committee's responsibility - and theirs alone - to decide the finals day format and any cutoff points.
They will likely have involved the sailors in establishing the principles, but at the time the cut is made they cannot expect (e.g.) the 4th team to volunteer to race against someone below them who might knock them out.