A data engineer manages a large Delta table that is partitioned by `country`. Over time, most partitions have become very small because many countries have few records, while a handful of countries dominate the data. Query performance is inconsistent, and OPTIMIZE runs are slow. The team wants a single approach that avoids the small-file and skew problems of fixed partitioning while still improving data skipping on `country` and `event_date`. What should the engineer do?