Go to the landing page, and it shows you an extract of a sutta. Press F5 and you get another sutta etc.
I’ve just tested 20 right now and it seem to be random enough, but looking at the code behind could help understand the scope of the random sutta feature:
Wow, I don’t even remember making this thread 5 years ago or even having a fledgling sutta practice that fizzled out! I’m guessing the anthology list I was referring to was the one I made from Bhikkhu Bodhi’s “In The Buddha’s Words” or the list of suttas I made from it.