Reading this maze
A second look starts at row 1, column 1. Of the 12 grid positions, 9 are paintable and 3 are walls. The start is already painted; the other 8 tiles remain to be reached.
Start right from row 1, column 1. The wall stops you at row 1, column 4; keep the side corridors available for a return visit. The first slide covers 4 of 9 target tiles; 5 remain.
The verified opening crosses 3 tiles before stopping. A breadth-first search proves a 5-slide finish from this exact starting board; that is a reference target, not a move limit. You may revisit any painted tile.