I agree with your method of using a regression test to save resources. But this might not always identify the issue. By using a less involved method first and then later a more involved re-executing full verification and validation protocols if not solved. However, the changes that are made can also involve the proper track to take. A minor change (in the opinion of the company) can implicit a regression test. However, a functional change will need a full re-evaluation. Each solution, even those not mentions are highly dependent on the situation.