Follow up is occasionally for years but generally months. Patients don't keep their providers very long in California due to managed care (and possibly because I'm a shitty doctor).
I use the lidocaine mainly as a test to see if I got into the right space. It's probably not necessary for this kind of injection but I do like my patients to get immediate relief. The steroids kick in by the next day. I would not expect lido alone to give relief for longer than a day. It's just a topical, short-acting anesthetic.