I have the 2020 model Ford Eco sport titanium with a built i sat nav. I don't use it as it doesn't do updates. So I've got a TomTom and hard wired it in. Trouble is and this is just a moan, practically every day there is a camera update. I take it in the house and update it then maybe later that day there's more updates. I reckon they must be putting new cameras up in the UK every day of the week.
Moan over....for now.

 

Is it because it includes mobile locations/roadwork avaerage speed that might change regularly?

 

Yes that's right, there's always road map changes and speed cameras throughout the year. They don't update on the built in one.

 

I had a garmin nuvi 200 that I used for well over 10 years. Never updated it once and had very little problems (used it in a truck 100's of times as well). Just always cross referenced the route with a proper map plus Google maps as well.
I do still have the little garmin but figured its probably going to give up on me in the not too distant future. So now I've just bought a wireless car charger with window mount for my phone and use Google maps. Still always cross reference with a map and if necessary adjust the route accordingly as I always have. With Google maps though its so much easier to modify a route. Loads cheaper than buying an expensive sat nav.