I mean they did have decently good mathematicians abord the ships who were already great mappers. An accurate time peice would help with accuracy… But nautical maps were nautical maps. More accurate ones are great but they did already have serviceable ones.
What’s wild about the cultural concept of your average maps of the period in a more general sense is they were often more conceptually philosophic and religious tools meant to illustrate a “you are here” for the soul. Geographic accuracy was at best a secondary consideration.