How Often to Change Filters?

How often would you reasonably change the following filters? Is it more dependent on mileage or time?

- Oil filter
- Air filter
- Dust/pollen filter.

Ralf.
Passat TDI PD115.

Regarding the air filter, I would also consider where I've been driving. To put it bluntly: if I'm doing a desert crossing, it should be replaced more often than usual. But I think you can generally rely on the 30,000 km interval recommended by VW. I have a K&N filter and wash it approximately every 30,000 km, but I don't drive on gravel roads or anything like that.
And you should occasionally check what kind of dirt and debris accumulates in the gutter, I've seen some real ecosystems develop in there (fallen leaves, etc.).

What are your thoughts on oil filters? Should they be replaced with every oil change, every 15,000 km? Or is it sufficient to replace them every second, third, or fourth time? In brand new cars with variable service intervals, the oil filter probably stays in for up to 50,000 km.

What do you think about it?

I'm not sure about the new cars, but otherwise, I think it's quite bad practice to not change the oil filter when doing an oil change. If you don't change the filter, there's really no point in changing the oil...

When I make coffee, I always use a new filter bag each time .