you don’t need to worry about cars on the side road. You just need to confidently finish your turn or keep going straight.
It’s always good to scan the side road at the intersections, but we don’t slow down TOO much to do that.
If the intersection is very narrow or because of some buildings or trees, you can't see the side road clearly, you need to slow down and proceed with caution. Because in case someone missed the stop sign, at least you can stop and avoid an accident.