I would think this was implied:

Only noobs like myself years ago would go ahead and refactor a lot of code during work hours without a good reason.

However when you stumble through something and finally understand the idea behind it (good or bad) then it might be a good time to add a couple of tests.

And when you have a few tests that covers nearby code you can hopefully find the courage to make a few surgical cuts to remove the worst tumors. ;-)