The way I tend to apply the less vs. fewer rule is:
- If I can count it, it's fewer - (Drink fewer glasses of water.)
- If I can't count it, it's less - (Drink less water.)
But when it comes to numbers and time, I usually see less where either less or fewer seem to apply, for example:
- Less than 24 hours ago
- Fewer than 24 hours ago
- 10 items or less
- 10 items or fewer
I can count hours and items, and I can count to 24 and 10, but I can't count a 24 or 10.
Even though I see less applied, which is actually correct?