Heat Map Seasonality
I live in the UK, here some trails can become impassable in winter, especially on clay soils where you're doing well to remain upright, let alone run.
I noticed your global heatmap is updated based on the last 2 years data. Whilst this is good for showing typically where you can run, it's nothing like as helpful in picking out routes that are possible to use in the depths of winter.
So... How about an option where all the runs from the last, say 5 years are used (to get enough data) but only for the current month, or the three months centered on the current month. That way we don't try and take ourselves down tracks that just turn into a bog in the middle of December (as I did on Sunday)