Everytime I have been in a speed zone under 55 mph, the curve advisory speed matches the speed limit unless the curve is sharper than the speed zone limit.

From my experience, usually an advisory speed is not posted unless the curve is requires a slower speed. In this case, the speed limit is 45 mph, and the curve is 45 mph, so the curve advisory signage should not have an advisory speed displayed. Simply an arrow and that's all.

A similar situation exists on a nearby road where a 45 mph advisory speed is posted on a 45 mph speed zone. In the past, the speed limit was 55 mph, and the curve required slowing to 45 mph. Now that the speed limit has been lowered to 45 mph, the sign is redundant.

On another road nearby, the speed limit has always been 45 mph, and there's a 45 mph curve that does not have any advisory speed posted, simply just an arrow. That's because you can take the curve at the speed limit with no issues. If you're exceeding the speed limit, that's your own issue.