Experience made many players question and change some behaviours they were absolutely sure were good in the first place. As we play and keep playing, we take reflexes that make us play faster and more efficiently. For example, we very soon learn that a single-card clue means "play this card". So we get used to this and systematically play any single-clued card.

However, with a few more games, people easily understand that single-card clues that hit the chop are different. They are very likely to be save clues, so people know to hold the clued card (suppressing the very basic, vital single-card 'play' reflex).

Now, most BGA Hanabi good players have gradually ended up realizing that playing 1s from the right was the best option (suppressing the very strong leftism reflex). That's awesome. It took a lot of time, but they have come to see reason.

However, in the case of in-game, non-chop conventional leftism, it is funny that people have such a hard time being convinced to question this reflex. They just won't do it. Maybe it will just take more time. Comfort is such a hard thing to give up on.

Even single-card clues are not as straightforward as they first seem. If clued X on one non-chop card, you tend to auto-think "playable". However, objectively, it only tells you two things: this card is X, all your other cards are non-X. This non-X part may be the key. For instance, all 1s have been played, except for Y1. No 2s are in play yet. You have two 2s you don't know the colour of. I clue you yellow on your most recent card. So your 2s are not yellow and you can play them! This is the only 100% sure thing.

The same questioning process should be carried out about a lot of moves. Drop equivalences like "clue type #47 = reaction #47". Analyse every situation and try to see what the clue means in that very situation. Don't think too fast, keep your head cool, consider all options.

When I was not yet the age where children have addressed equations at school a classmate came to school one day claiming proudly "x = 5" because his daddy said so.

Ok, so x = 5. Always. Right?