Full Rescan
Level: Advanced
Rescan every line involved each time you make a move.
In a nonogram, every time you confirm a cell the situation of the row and column it belongs to changes. The heart of advanced solving is the habit of rescanning the lines involved from the start whenever a confirmation appears.
A single new X or a single newly filled cell often makes overlap or block splitting possible on another line. Miss it and it looks like a deadlock, when in fact there is still a line left to look at again.
When you feel stuck, rescan the recently changed lines first. Most 'unsolvable' moments are resolved by a rescan.
Related techniques
Intermediate
Row–Column Cross-Reference
Reflect a cell confirmed in one line onto the crossing line.
AdvancedTesting for Contradiction
Assume a value for one cell; if it breaks a rule, confirm the opposite.