When I did half hour bookings they blocked longer bookings (had plenty wanting 1 hour or more), many would be late, require lots of texting to arrange, then would over run or use delay tactics eg say they wanted a drink or took up an offer of drink, talked/drank slowly then 20 minutes in expected the time to start.
It wasn't fair so I kept two regulars one who never over ran, never asked for anything complicated, the other paid a higher rate I set. I offered 45 minutes which was only taken up by 2 others and was busy enough with one hour and longer.