One purchase pause in Tower Defense: check coverage

Before placing or upgrading a tower, pause to inspect the path it can actually hit. Count how long enemies remain in range, whether terrain blocks shots, and whether another tower already covers the same section. Then compare that purchase with filling a gap on a second lane or saving for a coming wave. There is no need to imagine an opponent's next move if the mode is wave-based; the relevant question is what the next enemy group will do. A few seconds of coverage analysis can prevent an expensive blind upgrade.