Well, to be honest, most major city and rural roads and important routes will have 99.9% of the intersections signed. (either that, or the rule 'speed bump/side walk between small road and through-road means through-road has priority' applies).

However, in smaller town streets and on smaller rural roads, there will be no signs and the right of way is for the driver coming from the right. You will not find any signs even right in the centre of Amsterdam on small streets, for example (not that I would reccomend using a car in Amsterdam ever by the way). This applies to zones where the speed limit is 30 km /h (which is maybe 20 ish mph?). However of course every major road will be fully signed and the main road will have priority. I think this saves a lot of unnecessary signposting which is a good thing.

In Germany I don't think they have the rule of the 'speed bump/side walk between road and through-road' rule. I have seen that on 99% of major roads, the major road still always has prirority and this is signposted. But you might have to pay a little bit more attention than elsewhere.

Also keep in mind that if your traffic light is green and you want to turn left, the traffic that goes straight ahead has priority, so you may have to wait in the middle of the intersection. But I think this is common anywhere.