Look at the new neighbours
Imagine the row closing after a pair disappears and note which ranks will touch.
Prefer central removals
Pairs near the centre usually affect more cards than pairs along the outside edge.
Clear every pair before refilling
The stock is available only once no adjacent equal ranks remain.
Keep in mind
- Preview compaction.
- Prefer central pairs.
- Check diagonals.
- Exhaust pairs before refilling.