Do you need floor boards if laying realwood flooring?

[MoonMan2]

In the programme "Help me, my house is falling apart", a chap laid strips of wood across joists, he didn't bother with floorboards.

Last nite I was at an aquantance house and they had wood on top of joists too.

Is this normal?

I know that wooden flooring tends to be 18mm thick which would make it sit very high on floorboards.

 

[Chri5]

Certain 22mm solid wood system can.

Obvously the standard stuff in mixed lengths betwwen 400mm and 2000mm won't be suitable since the flooring system will need to be in decent lengths to be supported across the joists.