It absolutely is the shape that matters. A blue circle with an arrow indicates you MUST follow it, a blue square with an arrow indicates you CAN follow it. A blue circle with an arrow pointing forward can be replaced with a red circle with arrows pointing in every other direction, because it indicates a mandatory, I.e. you must eat the banana.
it varies. france and norway have some square mandatory “keep <direction>” arrows and sweden has the aforementioned “one-way in your direction” square arrow.
It absolutely is the shape that matters. A blue circle with an arrow indicates you MUST follow it, a blue square with an arrow indicates you CAN follow it. A blue circle with an arrow pointing forward can be replaced with a red circle with arrows pointing in every other direction, because it indicates a mandatory, I.e. you must eat the banana.
it varies. france and norway have some square mandatory “keep <direction>” arrows and sweden has the aforementioned “one-way in your direction” square arrow.