A mix of both, idgaf who you are you aint just about to drastically change a pilot on your first tv show without the producers hearing an explanation
once you start actually seeing the visuals you may have different ideas on how characters act and speak, how shyt might develop in the next season etc.
Script revisions happen on set all the time.
shyt i just finished a 10 episode show and we had to back and COMPLETELY reshoot the pilot halfway through because it didnt flow right with the rest of the following episodes
changed directors an everything