The convention in my area is to remove all clippings. I do not. Not even on the reel cut lawns. Makes no sense to strip away nutrients and organic matter only to have to hit the customer for a yearly application of bought organic matter. Maintaining sufficient nitrogen, proper base ratios in the soil, correct pH and mowing often enough makes it so that I have a hard time finding last week's clippings. This method, however, does not work if the lawn is on excessive nitrogen. I would have to mow daily.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738