I had a couple trading dishwashing chores for sheep. No.
It was my turn and it was clear that one person would win this round if no one won before him. So I made a hail-mary trade with someone else that gave me the slightest chance of winning, but it failed to do so. And of course, that person I made the trade with ended up winning because of my trade. We never played again.
I’ve played far more aggressive and complex games where we routinely turn on each other and we just have a laugh and keep playing.
In all games, within game contexts, you may only do things expressly allowed by the rules. This is what it means to have rules; it is the covenant you have agreed to by agreeing to play. You can play tic-tac-toe in a van while yodeling, but putting a Z in a box is out of the question. It is not up to any rulebook to say that you can't use a memory aid; rather it is up to the rulebook to specifically allow it, or else you can't use one. It doesn't matter how much the game for you is not about this memorization, how much the memory thing seems tangential to whatever fun the game provides; you do not get to use anything other than your brain to handle that memorization, unless of course you are explicitly playing a variant. You also do not get to - and this is important - scrawl notes to yourself on your belly using your own blood. Games between players are played between players, and "players" do not by default include notebooks or pencils, even makeshift ones that are constructed from the players. Expecting all rulebooks to repeat this is nonsense, and anyway would offend people who don't like to talk about blood.
Go explain to little Sally that she can't count on her fingers, because only her brain is allowed. Go tell players that they shouldn't fiddle with meeps because that could be a notation tool. No fun allowed, we're playing board games here.
Playing with three mostly fixes it, but then there are fewer people to trade with. Using a set, balanced board layout can help, but IMO gets kinda boring.
The reactions to doing moves that only hurt them, which otherwise have no personal gain and often cost you future opportunity, are absolutely priceless.
- Robber can only target equal or higher VPs
- Building a road within 2 lengths of opponent's settlement, and not in equal proximity to yours, induces a toll of one resource.
Or with the seafarers expansion! It's an almost perfect expansion to an already excellent game.
Playing with Helpers also modifies the game enough to try more strategies if you are stuck. The "Marianne" helper, for example, can really be a saving grace during a sequence of bad rolls for you.
And then come back and keep playing.
All other things being equal, the optimal placement of the robber is to impact the person on your right. This makes it longer before the person can retaliate against you (if retaliation is part of the way people play).