I've done my first HOT Humanitarian OSM Team contributions now in Khartoum, Sudan.
I think it's a fantastic concept, and it's nice to know and see that the 30mins or an hour actually helps a lot. Dry areas seem very easy to map like Khartoum, but I checked some areas in Aceh, Indonesia, and they are very complex. There's no way to see the road network due to vegetation and tree cover + the areas are often with cloud cover. Hopefully Charlie Loyd and MapBox are able to fix the cloud cover issue with their Cloudless Atlas project.
Also, did my first validation in HOT, too. Interesting to see how other contributors map, and HOT definitely needs some better advice how to tag tracks in the desert. I'm using surface=unpaved, or surface=sand, and highway=track.