The quantity of light reaching a camera sensor, as determined by exposure time (shutter speed and lens aperture-for DSLR camera).
Shorter subs would result in a lot more large files and longer subs would result in more time thrown out due to clouds, satellites, airplane trails etc.
Whether 6x ten minute exposures really do give you more detail than 12x five minute exposures?
What exposure time should I use?! Let's answer that!
Ideal exposure calculator in an excel sheet by Mariner 2 on cloudynights
https://www.cloudynights.com/topic/590093-suggested-sub-exposure-tables-for-asi071mc-c-and-qhy168c/