No Flags

Minesweeper is won by opening all safe squares. Flagging every mine is a waste of time. On Intermediate a NF player needs to open 216 safe squares, but a very inefficient Flagger needs to open 216 squares and flag 40 mines. However, an efficient Flagger can use chording can open multiple squares.

NF players look for openings instead of mines. Openings propagate in all directions until they are surrounded by numbers; if you click inside an opening you do not have to click squares with numbers! The statistic for board difficulty is 3BV, which counts the minimum number of left clicks required to clear a board. Numbers surrounding openings are not counted because clicking them is redundant. Low 3BV boards favour NF players because these have more openings with the mines grouped into islands.

The special skill of NF technique is "seeing" mines in order to use patterns such as 1-1-X and subsets to search for openings.

The only reason to flag the pink squares is to make them look pretty. You win by opening all safe squares, not by flagging mines.The only reason to flag the pink squares is to make them look pretty. You win by opening all safe squares, not by flagging mines.
The NF technique 'sees' the two mines touching the left 3 and uses 1-1-X twice to open the blue squares.The NF technique 'sees' the two mines touching the left 3 and uses 1-1-X twice to open the blue squares.
The NF technique 'sees' the two mines touching the 3 and uses 1-1-X to open the 1. The yellow squares will be numbers but the blue square could be an opening.The NF technique 'sees' the two mines touching the 3 and uses 1-1-X to open the 1. The yellow squares will be numbers but the blue square could be an opening.
The NF technique 'sees' the three mines touching the 4 and uses 1-1-X to open the 1. The yellow squares will be numbers (because there is a mine in the two squares above) but the blue square could be an opening.The NF technique 'sees' the three mines touching the 4 and uses 1-1-X to open the 1. The yellow squares will be numbers (because there is a mine in the two squares above) but the blue square could be an opening.

When a good NF player sees multiple safe squares, the ones containing numbers (which might be borders) are opened last.

Pink squares are mines and yellow squares will be numbers. The blue squares might be openings.Pink squares are mines and yellow squares will be numbers. The blue squares might be openings.
Pink squares are mines and yellow squares will be numbers. The blue squares might be openings.Pink squares are mines and yellow squares will be numbers. The blue squares might be openings.
Pink squares are mines and yellow squares will be numbers. The blue squares might be openings.Pink squares are mines and yellow squares will be numbers. The blue squares might be openings.
The pink squares are 50:50 guesses so the yellow squares will contain numbers. A NF player should guess a blue square.The pink squares are 50:50 guesses so the yellow squares will contain numbers. A NF player should guess a blue square.