Step 5 of 5
Work backwards
The finish is as fixed as the start. Begin from it.
The rule of thumb: The finish is as fixed as the start: plan the last stretch from the final dot back.
Everyone starts at dot 1. The last dot is just as fixed, and it has only one link, so it often has only one way in. When it does, that link is certain, and so is the next cell along if that one is short of exits too.
Trace the chain backwards from the finish for as long as each cell has only one open way to continue. It is the same exit-counting from step 1, aimed at the end instead of the start, which is why many players miss it.
The same works between any two dots: ask how the path has to arrive at a tight dot, then make sure the route out of the dot before it can get there. These practice boards need a chain that begins at the finish.
Where to look: The last dot, first. Count its open neighbors, then follow the chain while each cell has only one way on.
Worked example
A real position from a board that needs Work backwards. Purple ring: what the reasoning rests on. Grey line: links already known. Dashed: the edges in question. Green line: a link it proves. Red cross: an edge it rules out.
That is the whole track: count exits, close finished cells, commit corners, guard the ends, and start from either end. Time for a full board. Play a full board →