If you can be at front of line and have your sunscreen already on and flip flops in hand- fast walk to lounger at front of volcano- throw down stuff immediately- then speed walk to Krakatau, you can usually ride it 4+ times in a row before having to get off. Then once we have to get off we hit everything else as we’re ahead of the crowds.
Those first 30 mins while people are meandering around is the peak time to walk onto anything