Before the 1980s, there was no such thing as a release day for music. Record stores simply stocked the shelves with new albums once they arrived at the shop. Then once the industry became more competitive, an agreed-upon day to release new music was necessary to create a level playing field.
Tuesday was a date that was firmly rooted in a culture that printed, recorded, shipped, unboxed, and bought albums in their physical form. When albums weren’t digital downloads, they required a lot of manpower. By placing the release date on Tuesday, record labels had the entire weekend to ship new inventory across the country to record stores, and stores had a full non-weekend day to unpack albums and prepare the store for shelving. For artists, the benefit of releasing an album on standard American Tuesday release date is that, it made their album sales look better. Billboard creates the top album and singles charts every week, and those are published on Wednesday and tracks sale from Tuesday to Tuesday.
This ‘rule’ only applied to citizens of North America; in France, new music was distributed on Mondays and on Friday in Australia or Germany. This meant that a hardcore Canadian fan could illegally upload a new album for all their German buddies to check out 3 days ahead of schedule.
Thus, in an effort to combat piracy, Friday was chosen worldwide as a new music release day. Accordingly, all the bureaucratic details of streaming services and billboard charts were adjusted to line up with Fridays. Billboard tracks sales from Friday to Thursday each week, so a song or album released on a Friday has the advantage of being tracked for all seven days of the cycle. Most artists currently release music on Fridays, so it made sense for streaming services to update their new music playlists on Fridays too. In turn, artists are incentivised to drop music on Fridays and increase their chances of getting placements on those playlists. In other words, it’s a chicken-or-the-egg cycle that points to Fridays from both directions.