How many/what size hiding places ?

Hello,

After reading a lot about the importance of providing shelter for Malawi
cichlids, I'm still left unsure as to how much hiding space and what
size is necessary.

If I provide a big pile of rocks in the tank, then there will be cracks
between the rocks. How do I know if these are big enough ? Also, the
cracks are all going to be connected once they swim behind the rocks.
Will this be a problem ? How do I know if I have enough cracks and
crevices ?

TIA

--
Alan Silver