Yes it would be much better that all the distances were the same but that is not the French method of designing experiments.
The comparison between AnXI [M1803] and Gribeauval [M1765] cannisters undertaken at Strasbourg over the summer of 1802 [SHAT 2w 84-86] was in a long tradition of French Experiments.
To proove that the AnXI guns firing the new cannister was more effective than those by Gribeauval.
The service charge for AnXI guns which was smaller than the service charge for Gribeauval guns was used. As there were less gunpowder so less range for the Gribeauval guns.
The Gribeauval guns obtained less than half the range obtained in tests quoted in De Scheel (1777 rp1800) that I have quoted.
The AnXI design was remarkably superior in the 1802 tests. Under normal conditions where the correct service charge was used the AnXI designs were still superior but only slightly.
The tests were set up to proove the overwhelming superioty of the AnXI designs and not to be fair. As alluded to before the tests carried out during the 1770s when M1732 Valliere and M1765 Gribeauval supporters were trying to proove the superiority of each others guns. In one, half the weight of shot of powder was used to fire from the Gribeauval gun tube and no wonder it failed and the carriage as this was almost the proof charge. The normal service charge was a third the weight of shot. In another test Valliere guns were fire with third the weight of shot and did not have the range of the Gribeauval guns. The normal service charge was half the weight of shot. This did not proove anything. This is biased, misleading and pseudo-science.
This is unlike the tests carried out in Britain and Germany in the period.