My hose drains completely in about half an hour. If I check the flow
rate at the water meter when it first comes on, it dumps about a gallon
into the soaker hose. Valve shuts off in 2 minutes. Come back 5 minutes
later and cycle it again and there is very little movement on the
meter flow indicator as the water hasn't moved much out of the hose.
But, wait 30 minutes and cycle it again, and it will take another
gallon. My daily cycle is 2 valve open/closes about 45 minutes apart.

Of course, it may be that I have a fissure here and there over the 100'
run that drains off that water which the soil immediately around the
hose holes doesn't eventually take, I don't know.

The one structural engineer that talked to me about overwatering in
clay noted that the soil will take what it can, then just won't
supersaturate - the water just won't move out of the hose. He indicated
that foundation edge effects pushing up are far less bothersome than
the opposite - clay collapsing downwards due to extreme dryness, which
will cause serious slab cracking a lot sooner.

I can't tell you a thing about sandy soils. It's hard enough dealing
with the gumbo...

Bill