I've only recently started looking at Sudoku. Many of the methods in list are rather complex and very difficult to apply. But unless I missed it, there is a relatively simple method that isn't listed. First, consider the Row/Column Subsets rule.

Row/Column Subsets

If for a certain digit, there are N distinct rows each with 2 to N candidate cells and these cells fall on exactly N common columns, then remove all candidates for this digit in these N columns except for those that lie within the defining rows.

Am I really the only one who has noticed that you can replace either row or column with block and you still have a valid rule? Sudoku has some equivalent formulations in which there is no distinction between constraints. So generally speaking, any rule that involves rows or columns is going to have an equivalent one with blocks. (note that this rule with blocks is useful only for N=2, and it is undefined for N=4 or higher because at most three rows can intersect one block.)