When can you use game boards that you split out?

Galatea

I have been reviewing LGs and I am over thinking this I think...

You know how sometimes we split out game boards and make as many inferences at the beginning as we can?

When CAN you use those boards to answer questions, and when can you NOT use them (i.e., you would need to draw a new board)?

I am confused b/c sometimes I split out game boards, and the question reads something like "If J is in 4 then where must H be?", so then I look through my boards and find one where J is in 4 to see where H must go. But then sometimes I get those wrong... Because I did not create a new game board for the question...