modern engines with fuel injection are very intelligent indeed with their computerised ECU. the advantage of this is the engine does it tuning on its own at all time whether its cold or warm.
what normally people mean by tuning is simply on the maintenance side for air filter and spark plugs (clean or replaced for both items). EFI oso really need clean fuel supply, so fuel filter replacement must be punctual to avoid unnecessary stalling or jerking. other than that, EFI does everything on its own except maybe for engine idle level which u can adjust low as per specification or higher.
u open one workshop, then tell ur customer that ur car no need tuning one. how do u survive? so, must tell kena tuning one...
p/s tuning used to be time assuming for old cars with air filter and spark plug to start. then it wud be the contact point gap adjustment, then the distributor rotor cleaning, check timing then check need to tune the carburettor. a good tune will result good combustion resulting water vapour at ur exhaust tail pipe. that was the eighties...