Spirit box multiple regulators

[Quirkey]

I'm trying to read and understand more schematics. Looking at the Spirit Box - why are there regulators for each the pt2399 and the Belton Brick when they're both L05/5V? Why not tie them to the same rail? I'm guessing there's something simple I'm missing here so I'd love to know!

 

[Robert]

Most likely to prevent noise since the Belton Brick and PT2399 are both digital.

 

[Quirkey]

Ah. Noise from the IC's or from the regulator?