I learned a long time ago about working on motors and talking to the customer or anyone else. Never again
A friend many years ago lost an $$$ 429 Ford on start up due to an errant 1/2" bolt in a cylinder. Quite a few "Friends?" were helping/watching the assy. But generally speaking if they are well known they are either trusted to help or the work slows way down /stops. My Limit is typically 1, 2 or more things can happen so the BS starts until I can concentrate
A friend many years ago lost an $$$ 429 Ford on start up due to an errant 1/2" bolt in a cylinder. Quite a few "Friends?" were helping/watching the assy. 
