I was reading posts concerning slats for bed frames and want to know if it is necessary for metal frames to have slats before the box springs are put on the frame? I just purchased a metal frame for a full set and want to make sure before I put the box spring on it as no slats were included. If I should get them, what size should they be and how many?

I used two x ones cut to size and placed a foot apart across the bed before putting the box spring on.