As an LBS mechanic I would say it depends on how impatient the customer is to the OPs original question :wink:
In reality it depends on the manufacturer tbh, if it's a Pashley it would take minutes, if it's a Universal, weeks.
Torque wrench only really comes out for higher end builds or any carbon in reality.
For once I can also agree with TJ, an experienced mechanic does develop feel without doubt.
Suggesting you need your brake levers being as loose as possible is plain daft.