Spine surgery is a pretty creative field. If you present a case to 10 spine surgeons you'll get 11 different opinions from do nothing to multi-level corpectomies. It's all about patient selection.How many different procedures do you do as a spine surgeon?
The basics are decompression and stabilization. Decompression can be from the front or back (ACDF, microdiscectomy, laminectomy, laminoplasty, +/- facetectomy, foraminotomy) and some can be done open vs. MIS. You may also need to do a corpectomy to decompress the spine from a big tumor or whatever. Stabilization can be just posterior fusion (open PSIF, perc screws) or with interbody fusion (ALIF, OLIF, XLIF, TLIF, etc.). Some of these can be done open vs. MIS as well.
The art comes in figuring out from the history, exam, and imaging what combination of the above the patient needs and what the chances are that the surgery will help. Everyone has back pain. You can look at spine imaging of anyone over 40 and make a case for a 1-level TLIF with PSIF. It's a sweet case. The problem is it will only help if the patient has the right symptoms, and if they don't get better you will be stuck with them forever and end fusing them from T10-pelvis and dealing with broken and infected hardware when they never should have had surgery in the first place.