Every QA person uses a bug tracker. I had thought all our teams used bug trackers religiously. Turns out some of our QA people have adopted the idea that they should just walk over and talk to the developers and show them when they find a bug. Often those bugs get fixed quickly and never enter the bug tracker. If it’s going to be a significant effort to research and fix only then does it go into the bug tracker.
Another sign that our Agile adoption is taking a deeper hold. The point of QA is to improve the quality of the code. Fixing a bug when you find it is a better practice. Bug trackers can still be handy, but for a collocated team they’re less important.