This has been discussed and complained about quite a few times 
There are Long threads and Wheel Skirts and people running around their machines with a broom.
In practice, wood dust doesn’t seem to matter much, at least when using the large diameter rollerskate wheels (I do not have LR3 so I don’t have experience with the bearings based design).
That said, with my LR2 I simply used the center of the table as much as possible and avoided cutting activity near the edges. Truth to be told, I was more concerned about sawdust piling on lead screws so I was thinking about printing a pair of Lead screw Covers but judging from the pictures this is not an issue with LR3 or even if it is, it’s easy to resolve with a short brush strip.