Is “workload” ever a countable noun? Can it also be uncountable?

Question

Here are two sentences which have almost the same meaning that I have found in two different dictionaries:

1. Teachers are always complaining about their heavy workloads. (Cambridge Dictionary)
2. Students complained about the heavy workload. (Merriam-Webster Dictionary)

Both citations show a plural subject, but the grammatical number of what those subjects are complaining about is inconsistent.

So, should I use singular/uncountable workload or plural workloads in a sentence sentence like:

Not countable:

3. They have heavy workload.

   (Like saying that “They had great contentment” or “They breathed fresh air”.)

Countable:

4. They have a heavy workload.
5. They have heavy workloads.

Or are both possibilities admissible here, depending on whether it’s countable or not? If both are meaningful, do they both mean the same thing, or does each mean something slightly different from the other?

Answer 1

A student can have his or her own individual heavy workload, which is countable, thus they have heavy workloads (plural), or students in general can have a heavy workload (generic, abstract, non-countable) - they they have a heavy workload. Which you choose depends on whether you are considering the students as individuals or generically.