Here is how I would expect a pro to spray paint kitchen cabinets. An amateur job should follow the same path. A brush painted job would differ slightly in that you wouldn't hang the doors to paint. You'd place them on a work table or easel instead. It's time intensive work, and should take 7-14 days to accomplish completely and cost between 7K-9K depending on kitchen size and amount of detail in cabinets.

Remove doors and drawer fronts.

Remove hinges and hardware.

Clean with TSP (tri-sodium phosphate)

Rinse and let dry.

Scrape any loose finish.

Fill any damaged spots or hardware holes that won't be reused.

Sand fill smooth.

Scuff sand the rest.

Tack off dust.

Hang in dust free paint booth with wires through hardware points.

Tack off dust again.

Spray with shellac based primer.

Scuff sand again.

Tack off dust.

Spray with second coat of primer.

Spray with first finish coat of a polyurethane enamel Or conversion varnish.

Spray with second coat.

If glazing is to occur, that is next.

Spray with clear over glaze

Add more molding or decorative details to boxes, filling nail holes and sanding smooth.

Repeat prep process with face frames and exposed cabinet sides using plastic to create a spray booth on site. If interiors are to be done, they are done before face frames and sides. Interiors are difficult, and add both time and expense to the job. Most interiors are laminate and don't accept paint well.

Allow everything to fully cure. That's 7-14 days.

Clean hinges and hardware and clear coat if you're keeping the old hardware.

Install new (or old) hinges and hardware.

Re-install doors and drawers and adjust for proper clearances.

If you are receiving or doing a job without this amount of effort, then you are not getting a quality job.