What do you guys normally average with the TB48? I know it says 18-22 mins or something likve that but wondering what people really get. This is with a x3

It can range from 15-20 minutes from most aggressive to most conservative until 5% battery. Battery life can also affect it downwards.
So for me it's more of
15-20. 18-22 is prolly without the camera or in controlled lab conditions

Between 16 and 17 minutes flying down to around 20% (3.5v per cell)
Nobody in their right minds would fly a pack down to 5% unless they wanted to lose their Inspire.
In windy conditions it can be as little as 14-15 mins but I would say around 16:30 is about 'average'