even in this day and age, some mechanics these days dont know that gap is different for XE (1300cc 2E) and GLI (1600cc 4AFE) engines of corollas of yesteryears.
I once went for plug change, I didnt know what gap the mechanic chose for the new plugs. As soon i fired up the car I knew something was wrong, mechanic said 'thora chalaen theek hojae ga'
I'd driven nearly to home but then i drove straight back. and i asked him to adjust the plugs to 0.8mm gap. He did that and problem solved.
bottomline: ajkal zada tar log kaam chor hain, they will try their level best to get you off their backs if a problem arises that requires a little brain function.