Grammar: fewer or less?
You've got to admit: 'fewer money' sounds odd. Some people feel the same way about 'less items', 'less people', 'less cars', 'less boyfriends' and all sorts of other things.
If you say how many, then you say fewer.
If you say how much, then you say less.
So, less for time and fewer for countables. A certain brand of tortilla has the following (correct) cooking instructions: "Microwave for about a minute for six, and less for fewer."
Air, water and time aren't countables, so less of them is OK. But if we're talking about actual items that you can separate, or countables. you will be more well liked if you use fewer instead. So, less money, less time, less milk, less credibility; fewer cabbages, fewer items, fewer friends, fewer problems.
About the author
Jesse Karjalainen is the author of The Joy of English: 100 conversations about the English Language, Cannibal – the language and history of the discovery of the New World, and Roanoke – the language and history of Early Colonial America.