Experts have learned schemas for identifying important categories of problems. These problem schemas are based on features relevant to the selection of solution procedures. Problem solver may learn new, useful problem schemas. Old rules might be recombined into new, more efficient procedures. Experts have more solved examples to refer back to.
Some evidence supports the notion that some problems are solved by restructuring and sudden insight.
Parallel Constraint Satisfaction Restructuring suggests that parallel processing may be an important component of solving ill-defined problems. There have been many successes in using parallel constraints to solve ill-defined problems faced by the visual system.