Blowouts and blur are usually geometry problems you can see in advance. Here is what drives them and how to preflight for them.
Ink migrates a little as it heals. When two lines sit too close, that small spread is enough for them to touch and read as one mass. When a line is too thin, the same spread swallows it. Both are about distance in millimetres, which means both are visible before the needle if you measure.
Minimum line width - how thin the thinnest stroke is. Line spacing - the tightest gap between separate lines. Black density - how much solid fill sits in one area, which increases trauma and spread. A merge-risk map shows exactly where nearby ink is likely to join after healing.
A touch-up costs a second session and a bit of trust. A preflight check costs a minute. Measuring width, spacing and merge risk at real size turns 'this might blow out' into a specific, fixable location on the design.