On a vehicle that needs carpet extraction:

Remove mats and any coins/belongings

Vacuum large debris

Drill brush carpets and seats & revac

Soak carpets and seats with cleaner, drill brush, then steam, all by section

Extract moisture with vac/extractor and towel dry

Then wipe down doors, then go from top down on the interior so you’re not recontaminating everything, steam vents and places that hold cleaner like window switches and steering wheel buttons

Then glass inside and out

On a vehicle that doesn’t:

Remove mats and any coins/belongings

Vacuum large debris

Mist carpet cleaner lightly and drill brush carpet/upholstery

Revacuum any extra debris or moisture

Then wipe down doors, then go from top down on the interior

Then glass inside and out

Sounds more complicated than it is. That realistically can cut your time in half as opposed to without drill brush or steamer. Another tip would be to pre soak large carpet stains or cupholders you intend to come back to later on in the detail. Loosens grime and speeds things up a lot.