Name one example.
That would be:
[Playful banter between two old friends, Kirk and Scotty.]
It was also the advice he gave to Geordi in 'Relics' - and he was shocked Geordi wasn't regularly inflating his timetables to make himself look good.
It was also corroborated by all the times when he needed unrealistically less time than he reported to his superiors for completing a task.
If that was a joke, well, Scotty put the joke into praxis repeatedly.
As for examples - watch TOS; you'll find plenty. I don't feel like going over TOS episodes just to entertain your butthurt.
Thank you, I've seen every TOS episode many times over. But at least we've established that you have no examples.
Your google fu is weak:
http://tvtropes.org/pmwiki/pmwiki.php/Main/ScottyTime
It even has a trope named after it.
Not that I need examples to prove Scotty's practice. 'Relics' fully establishes it.