There is no need to send your employee for a medical check-up if your employee does not show any signs of being medically unfit for the job. In general, you can presume your employee is medically fit.
If there are signs that your employees are medically unfit, you should send them for medical check-ups on a case-by-case basis, without having to send all employees in the same job for medical check-ups.
You should also send re-employed employees for medical check-ups if it is a job requirement that is applied to other employees with that job scope.