An X-panel is a 9 by 9 table with a header line across the top, representing the cells of the grid. I have one template sheet with 9 X-panels, one for each value. For puzzles surviving the bv scan, I pause to transcribe candidates of each value X into their X-panel. Clues are not transcribed, just candidates. An immediate value is the check on the accuracy of the slink marking on the grid.
X-panels concentrate attention on interactions between candidates of the same value, across the grid. As each X-panel is completed, it is examined, first for fish, and then for X-chains and loops. X-panels are updated as solving progresses. After several more stages, the X-panels are examined again for pattern analysis.