Hi Chris. This time I used GaiaGPS' Topo plus Sat layer maps - both offline (sub needed) on a
cheap Samsung tablet.
Plus of course, a lot of annotating beforehand.
GaiaGPS' rendition of OSM data on the Topo layer is bafflingly good (same in Morocco). I don't know how but they somehow know where to draw the [right] line when it comes to splattering a map with tracks and other detail – a common flaw which ruins the clarity of OSM-derived maps for nav purposes, IMO. I'm not sure the (OSM) North Africa Topo would have been as good in Alg which gets little user input these days.
Plus I experienced the novelty of live sat nav across the landscape – the holy grail of desert nav people were trying 20 years ago.
But some mornings GaiaGPS would take 20 mins to connect with itself, and for
recording tracks and wpts, it was unreliable, or perhaps the slightest touch of the screen stopped recording. A fixed mount as opposed to sat on my lap may have avoided this.
If my 650 Montana had a brighter, bigger screen but didn't cost £700 to upgrade to 700, I'd use that (as I do on a moto).
Southern Algeria being what it is and me and the driver knowing it well/up for trying new routes, we could pretty much navigate by landmarks (distinctive isolated mountains or passes) and find the best way between them.