Euro 5 D5 - DPF regen, how often?

[reggit]

Hi all,

Does anyone know a ball park mileage you’d expect the DPF in an early E5 D5 (205bhp) to regenerate? I’ve been chasing what I perceive to be poor mpg since I got the car last summer, with COVID it’s not seen a lot of use (like most others I guess).
Anyway now I’ve been able to get some mileage up, I’m using an ELM327 and a car scanner app to monitor the DPF soot level and see how often it initiates a regeneration cycle. I’ve found that with 85% motorway driving at 75ish (adaptive cruise set to 75 so it’s up and down a bit with traffic) the DPF is full and regenerating at around 330 miles.
Not had one of these ‘modern’ diesels before, so unsure if this is expected mileage to fill it with soot, I have a mild turbo whistle that I can hear with the window down, and am wondering if I’ve a mild boost leak somewhere. Vida not showing any related codes,
Car is as per my sig, but approaching 174,000 miles now.