Yes, I answered it - and in my experience, and I do have relevant experience, it’s not acceptable unless (a) blocking and (b) properly agreed and documented in the agreement that downtime waiting for client is billed at full rate. YMMV - either way, unless blocking is common, the day rate vs hourly rate is just a change of unit. Blocking is not common in well run projects I’ve been involved in, and not even in those that were badly run (though more than the well run)