Yes, using LIMIT is generally a good idea, especially when:

• Testing or debugging a query and you don't need the full dataset.

• Verify that your joins, filters, or computed columns return the expected results.

• Working on a large table, and fetching all rows could impact the performance.

In terms of your 2nd question (where should I put it in the order):

SELECT *
FROM employees
WHERE department = 'HR'
ORDER BY employee_id DESC
LIMIT 10; <<< at the very end of the query