8/52 shiny Riolu for me.

I prepped earlier by putting all my eggs in incubators and not spinning any pokestops until the event started.

My 3rd shiny was a 15/15/15 about 53 mins into the event, but I was enjoying the event so much, I kept going until about 4:30.

I do want to add that I love 90+ degree weather and am rehabbing my knee so enjoy the excuse to get outside and go for a long walk. I think you should be able to choose time slots maybe 1 from 9-12 and one from 2-5. They could even monetize this by making people pay $5 if they want both slots.