Hi Mark and welcome. The rings are to add stability to small or narrow pieces although they can affect dust control.
Normally for the largest bits you don’t use any rings but you should have at least a small one and a midsize one. That’s how the Grizzley insert plate comes. Your router has a built in cooling fan that sucks air in from the top and pushes it towards the bit which also then pushes dust away. All of the dust is created above the table so with small clearances around the bit there won’t be be much air flowing through but there also isn’t much room for dust to go down. A wider gap means more air going through the gap. Where you can wind up with problems is when you try to get everything to reverse direction by trying to suck it back down by enclosing the router in a box and putting your dust pickup under the router. I believe it is Herb Stoops that solved that by adding a tube that connected outside the box to the router intake so that the intake is not affected by the DC. In fact, with that configuration cooling and keeping dust out of the router are improved.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.