Should I track profit on each job?
Short answer
Yes, by job type at minimum. The shops that don't can't tell you which work makes money. They guess, and their guesses are usually wrong.
What to track
Revenue per job. Labor hours per job. Material cost per job. That gives you gross margin per job. Once you have 20 jobs of one type, you know whether to do more of it or stop.
The surprise
Most owners discover their most popular service has the worst margin and their least popular has the best. Then they restructure. The data is worth the 5 minutes of capture per job.
Ask your version of this question
This is one business owner-tested take. Your shop size, trade, and team change the answer. Ask the exact version inside Ask a Shop Owner and get a response grounded in how owners like you actually handled it.