When to fold.
Folding means abandoning your hand plan and switching to purely safe discards. It costs you the win but protects against large payments. Over a long session, the players who lose least tend to finish ahead of the players who win most.
Any opponent has three exposed sets. They need only one tile to win. Any discard from you is high-risk.
Wall is under 20 tiles and your hand is still 2 or more shanten from tenpai. You almost certainly won't finish in time.
You are holding demonstrably dangerous tiles with a marginal hand. Weigh the potential win against the payment risk.
Folding is not giving up. A fold that avoids paying 6 faan is worth more than winning at 3. Players who can't fold when they should consistently overpay across a session.
Not all tiles are equally dangerous to discard. There is a rough hierarchy — use it when you're under pressure.
If an opponent has already thrown a tile, that exact tile is almost never their winning tile. Copy their discards back under pressure.
A tile with 3 copies visible has only 1 remaining. Four copies visible means completely safe — it cannot be anyone's wait.
If an opponent discarded a 4, tiles 1 and 7 in the same suit are probably not their winning tiles either — they had no use for those sequences.
Discarding one tile from your own pair is relatively safe when folding — you know exactly how many copies are live.
Suji extends the neighbour logic into a structured system. When you know which tiles an opponent threw away, you can infer which tiles they are probably not waiting on.
If an opponent discarded a 4, they weren't holding 2–3 (they'd have wanted the 4 for 2–3–4) or 5–6 (they'd have wanted it for 4–5–6). So 1 and 7 in the same suit are likely safe — suji of the 4.
Suji doesn't cover pair waits, edge waits, or special hand shapes. An opponent could be waiting on an isolated pair that breaks the chow-logic assumption entirely. Treat suji as a probability filter, not a guarantee.
When your hand clearly won't win — too far from tenpai, dangerous tiles to hold, strong opponents building fast — manage the loss rather than chase the win.
Defense improves gradually. Most players develop offensive skills first and defensive skills years later. If you consciously practice the fold decision — even just recognizing three exposures — you are ahead of most beginners at the table.