Liability projections require assumptions for a number of variables, including mortality, early leavers, inflation and other factors.
Actual experience of these variables will cause the liabilities at any point in the future to differ from the projections, which will in turn influence contribution rates and the like.
For example, increasing longevity will lead to increased liabilities (and hence to increased contribution rates).
2. Career planning.
For an individual, experience generally relates to their past work - especially relevant work - contrasted with academic studies.
Volunteer work can also be relevant experience.