The obvious exception is when building a race engine. Since the average high performance engine has 2-3 times the bearing clearance of a street engine when it's built, and it's not expected to last very long, it's necessary to run an oil pump capable of keeping all those big clearances filled with oil. Most of the round track engines I've built over several decades were totally worn out with less than 1,000 miles on them, if they lasted that long before hand grenading. I built them with more clearance brand new than a 100K mile street engine would have. They were producing at least three times their designed horsepower and running way above their max RPM, so loose clearances were an absolute must to keep them from tightening up and seizing prematurely.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!