Board Game Arena

Hi, I'm new to BGA and relatively new to Hanabi (I've played it for a couple years but very infrequently and with a small pool of friends IRL) and I love it.

I jut read the tips and it was really enjoyable to see the conventions and smart play, some we figured out, some we didn't (at 3+P we say all marked cards are playable unless counter order, so the conventions are bound to differ quite a bit).

One smart play I didn't see mentioned for 2 players, and I wanted to know if it exists, how it is called and how common it is, is the following:

Discard a playable card to signal the partner has it in their hand, in the position of a prompt (leftmost compatible marked card, if any) or of a finesse (the draw).

Hence the names I chose: prompt discard and finesse discard.

It nets a safe discard, and in the case of a prompt discard, gets rid of a useless keep. Can also be used to balance the number of kept cards among players. It does not sound like much, but I think it represents a lot in 2P games where hand-lock is a recurrent issue.

In theory in could work for 3 players, but I think it can get into the way of a reverse finesse, but I do play it IRL in 3+P (where we have different conventions). I'm usually frowned upon but understood.

I don't know/care about the naming, I think some call it "gentleman discard", but this move is here - widely used on any player count. (EDIT: It is widely used on Expert&Master tables. Not sure how it is elsewhere.)

It has also other advantages you didn't mention of, more even important than balancing the hand, especially in 3+p. Generally - letting good cards on chop to be kept longer without a clue. Especially worthy move in case of cards we wouldn't clue unless a certain playcard is drawn. And in some cases, preoccupying another player with a play because of needing to save sth on him later. And +1 clue-token that gives extra info

Also, for example:
(one 3g copy was already discarded, 1g is on the table already but 2g not)
player A hand: 2b[play] x x x 3b[known], he plays 2b,
player B discards and his hand is now 3b x 1g 3g[unknown] 5[known]
A will have to save 3g one way of another. Not very useful to do it with marking trash 1g (and by some players that could be read as a "play 1g" clue) so it would be clued likely by 3, markng 3b later anyway. So instead of cluing 3s now, A discards 3b, B plays 3b and as he drawn another card, the situatio may changed - new play clue? Or as planned before, 3-save clue.

Check this game: https://boardgamearena.com/table?table=62984287
Literally everything green that was clued on me (1g2g3g) sooner or later was on partners hand and I discarded it, e.g. first 1g discard - saves 4g for longer (but also makes it a long time until 1g is played - after all the 1s that were clued... so the flow have to be considered when doing the discard, sometimes it might be too much slow-down if one person has all plays)
(If replaying it, notice also that I could discard 3g without full knowledge if it was 3g or 4g - because they were both on dk hand.)