For now this is just curiosity; I haven't got a specific project in mind.

If you build a table top from solid wood boards and you want to cover
the end grain with other (narrower) boards running perpendicular to the
"field" boards, how do you fasten the ends?

I think I get that you can't attach them rigidly, but how do you allow
for some play without there being obvious play? Tenons on the ends of
the main slats with extra length in the mortise on the ends? Then just
screwed in on the bottom in oversized holes?