Is it pitched properly?

I don’t always put the fan on and it’s not above the shower, but I can try that.

Get a Panasonic Whisper that turns on and off based on ambient moisture levels in the bathroom.

Mine works fantastically as it turns on when someone showers and then off again after about 30 minutes. Everything is always dry - no condensation on glass doors or mirrors either.

I have a linear shower drain and in the 4 years I've lived here, I've NEVER had any mildew on it. But then again, like everyone says, I always use the vent fan and keep it on for 30 minutes post shower. The vent should be right outside your shower, not in it.

Do you know what brand it is?

I have a Schulter linear drain and I do have to de gunk it every couple of months (clean the hair trap). For your fan get a countdown timer. When I get in the bath I hit ‘60’ and it runs for an hour. Problem solved.