@Avidfanofstuff very interesting! As @JoshuaT said, it’s hard to say what exactly is happening here without more details. We’d need to know whether or not your salary comes in as BACS or Faster Payments and if the official value date of the payment is Friday or Monday. I could imagine that they’re doing something clever where if Friday is the second day of the clearing cycle they will just credit your account a day early.
As a general rule, we’ll make the funds available to you as soon as we can 