Just look at maps of this time, the use different projections, different techniques, gather incomplete testimonies, often from a single expedition.
If you were an explorer, it was essential at the time to understand how the maps were made and what their weaknesses were. And instruments failures and bad weather could combine to prevent you from knowing your position for days. You needed to hack a measurements from 4 stars visible in a hole in the clouds.
If you were military, it was possibly even more crucial. Being able to quickly move from one point to the other, to avoid critical reefs or better: navigate through them, guess where a given ship will end up at which time, etc... were crucial skills.
If you were an explorer, it was essential at the time to understand how the maps were made and what their weaknesses were. And instruments failures and bad weather could combine to prevent you from knowing your position for days. You needed to hack a measurements from 4 stars visible in a hole in the clouds.
If you were military, it was possibly even more crucial. Being able to quickly move from one point to the other, to avoid critical reefs or better: navigate through them, guess where a given ship will end up at which time, etc... were crucial skills.