Great task you’ve set yourself. Are you using Strava heat map to identify the most popular bike routes (road and MTB)?

This may help focus your efforts?

I use this extension to get the URL of the heatmap with my Strava credentials:

https://addons.mozilla.org/en-US/firefox/addon/josm-strava-heatmap/

You have to reapply it each week or so as the login expires. Minor inconvenience for the benefits it brings in finding unmapped roads and trails.