Your understanding is correct. Although things are always changing. I will tell you what I experienced 15 years ago. We dove and spear fished under the bridge, and we dove the jetties at Radio Island. Those were the popular walk-ins at that time and in that place.
The walk to the jetties was very long indeed.
Simply amazing how far one will carry gear when one is determine to dive.You must dive high tide or there simply isn't enough depth to make it worth your while. When high tide finally came, we made our way to the far side of the jetty (the jetty runs parallel with the beach) and we worked our way to the bottom looking for sea critters among the rocks. There were a few that day. Nothing to write home about. When I got to the bottom, it seems to me it was around 15 to 25 feet deep at high tide, I layed on the warm sand and it felt good. Then I heard something HUGE slowly approaching. I layed there as something with a large slow churning giant prop made its way past. I said a little prayer and hoped I would not get sucked up into it. By the time we had burned one tank the tide had switched and the water was quickly headed out to sea.
The way to dive tidal situations is to be prepared when the tide is coming in. When it starts to slow down, it is time to get in the water. As you are diving the tide will continue slowing down and finally stop. It will not stay stopped for long. After it has switched direction and starts going out, it is time to end your dive.
Here is a link to a map of where you park and where you dive. In between, you walk, with gear.
Radio Island