For matched mesh, i think you mean like picture below:
But if we would like to simulate Press-in assembly,
because the diameter of Shaft is different from the diameter of Shaft sleeve, modeling in NX,
then how to create matched mesh?
do we need matched mesh for this case ?
Always having matching meshes in both source & target regions is good for contacting problems, you will have the best accuracy is stress results, and the most important: if you reverse the connector, the results should be more or less similar, not totally different, then the error for wrong identification or definition of the source or target regions is neglected or minimized, OK?.
In contact problems (not press-fit problems) where non-desired or artificial penetrations exist caused for not having matching meshes + the use of parameter INIPENE=0 then you will see hot spot stress results. NX NASTRAN do the job correctly, solving the interference problem caused by the "artificial" mesh penetration.
My suggestion is always use matching meshes, specially with low-order elements, or use high-order elements making sure to have midside nodes located in the surface geometry, not in the middle of straight line between corner nodes.