Quickest job on my Mk2 was fitting the weighted shift rod, no more than a minute. I have assisted with replacing an engine and gearbox for a Saph Cossie, which took a little over 3 hours, that's from it driving into the garage to driving out again, which I thought was pretty good.
Quickest job has to be replacing the std side repeaters with smoked ones, 45 seconds per side. Front engine mount on the mk2, 10 mins including bringing car into the garage, putting overalls on, engine up, mount in, torqued up and tools away.