"Etiquette", in my opinion, involves things that are not actual rules of the game. Things like being polite when chatting or not taking more time than necessary (the timed component of the game not being part of the official rules). By "more time than necessary" I mean things like getting up for a snack or taking a minute to chat outside the game between moves--focus should be on the game rather than elsewhere. If you get a phone call or your kids needs something, excuse yourself in chat (just say "brb") before taking a moment away from the game. That's polite. That's good etiquette. I recognize that what is "good etiquette" may differ from person to person, which is sort of part of the definition of "etiquette" and something that makes it different than "rules". Playing to win by playing tiles that make it less likely your opponent can score more points is covered by the rules (allowed) and ought not be thought of as "rude" or "poor sportsmanship" or "bad etiquette".
There may be people who are playing just to fill the board or to complete patterns or whatnot without necessarily caring whether they win. That's fine, but these people should not complain when someone playing to win gets in the way of their objectives. The default expectation ought to be that people are playing to win within the structure of the official rules.
Someone has mentioned playing defensively in the last round when the outcome has already been determined. Get over it. There's no reason for someone not to make the best plays when the outcome is no longer in doubt. If you feel time is being wasted, just concede the game and move on. Also, don't complain when someone concedes with only a turn or two left in the game and denies you the pleasure of seeing the scoring unfold.
There may be people who are playing just to fill the board or to complete patterns or whatnot without necessarily caring whether they win. That's fine, but these people should not complain when someone playing to win gets in the way of their objectives. The default expectation ought to be that people are playing to win within the structure of the official rules.
Someone has mentioned playing defensively in the last round when the outcome has already been determined. Get over it. There's no reason for someone not to make the best plays when the outcome is no longer in doubt. If you feel time is being wasted, just concede the game and move on. Also, don't complain when someone concedes with only a turn or two left in the game and denies you the pleasure of seeing the scoring unfold.
GL!