How long should one workspace exist? Best Practice Help!

Hey folks, I’ve been a loyal user and advocate of Asana since 2012 for our internship team. They’ve been working on projects under one workgroup since the beginning and there are it feels like 1M completed tasks. This makes search very messy when looking for old tasks. Do I dig in and delete old tasks and migrate current tasks to annual renew or should we just start over in a new workspace to clean it up?