[Solved] The date of the gallery

I'm pretty sure it's date uploaded, because there are sets from the same shoot (multi-part ones are the ones that are most easily recognised but I expect others may also be taken at the same time but released separately, like Alisa I's studio shoots) yet part two has a date added entry years after the first part.

Sites that share daily content are uploaded the day they are released (except weekends), while in most cases where it is also 'newer' content (for example within last week), we use the date of when it was uploaded. However, the original old dates are used when we're doing older content (several or more years back). Cheers!