How many times do you see people enter intersections like a "give way" or roundabout and have to stop suddenly because they had unexpectedly had to give way?
If this has happened to you take it as a warning sign that you are not expecting the unexpected.
Most of us travel the same routes over and over again and there are probably certain intersections where we get complacent as we rarely have to give way there.
My advice is to treat every intersection where you are obliged to give way (including roundabouts) as if there is a very good chance that you will have to stop and give way.
If you drive into the intersection at a speed chosen because you doubt you will have to stop then you are going too fast. That one time when you do actually have to give way will result in a best case of a sudden stop that is uncomfortable for passengers and perhaps embarrassing, and a worst case of a collision.