The 4mm is very strong but if you look at the bigger openings the strands are thicker.
For the grainy material like mono, the grit is 2mm so you can easily fill in the 4mm square hole with aggregate rather than cement lime paste. This imo can give you a sheet of plastic between passes. Delamination possible.
But in my experience it is the water running down the close strands that gives problems. I have had slide off.
So I prefer the bigger holed mesh. More pasty material gets pushed through so creating a better wet on wet bond. But also less chance of slide off.
Direct Building Supplies and Wack sells the bigger stuff. Parex do the tv10.