1 for the first 300 m, 1 more for the 2nd 300 m, 1 more for the 3rd 300 m and 1 more for the next 200 m. A total of 4 tests.
If you had a run of 290 m, you would have to do 1 test. You could not omit the test with the explanation that the production run was less than 300 m, thus no test was required.
Al