Attaching Top--Formula?

Hiya, I'm wondering if there's any sort of "standard" for how many screws to use to attach tops? I've got a top that is 24Wx58Lx3/4 thick that's going on top of a dresser carcass. I plan to screw the front edge of the top and use slotted holes along the sides/back to allow for movement. I'm curious to know how many screws I should be using on the front edge? The top is cherry. I have the option of screwing through the carcass at the front through either cherry or hard maple. If I were to screw through the hard maple, it would mean the front of the top's edge would be about 6" away from the screws (versus around 3" for the Cherry)....is this a problem? Sorry to make this simple affair complex. Cheers, cc