Arkadiy writes:

wrote:

The water should get to the pump, under the slab, before anything is
wet above.

Does this mean a french drain inside the basement doesn't make sense?
Or is it a backup thing (if the water does reach the floor)?

It doesn't mean that at all.
Water won't flow freely under all edges of the floor to the sump.
That's what the french drain does.

The pressure of the water against the cement causes the water
to come right thru the cement.
My basement used to form a puddle right in the middle of the floor
without running in from the sides.

Also you don't want to go too deep with the sump pump.
You'll end up trying to pump out the water table, wasting
electricity.