Every build gets fully tested at maximum TRACE logging, so that anyone who looks at the build / test later can search the logs for the bug.
8TBs of storage is a $200 hard drive. Fill it up, save everything. Buy 5 hard drives, copy data across them redundantly with ZFS and stuff.
1TBs of SSD storage is $100 (for 4GBps) to $200 (for 7GBps). Copy data from the hard drive array on the build server to the local workstation as you try to debug what went wrong in some unit test.