I had a client (potential client) schedule a call. We agreed on the time. However they did not show up for the call. This time was blocked out on my schedule which means it then becomes unavailable for other clients. I think it would be fair if someone schedules a call and doesn't show that the experts are compensated for their time. Time is money!
I think a deposit requirement would be NICE via Clarity... however, that would also reduce the overall number of conversions. So... just roll the dice and if someone skips a meeting, make sure to take that hour and do something productive for your OWN business ;)